Determine if a string is squeezable: Difference between revisions

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=={{header|8080 Assembly}}==
<lang 8080asm>puts: equ 9
org 100h
jmp demo
;;; Squeeze the string at DE on the character in C.
;;; The result is written starting at HL.
squeez: mvi b,'$' ; Last character seen
dcx d ; Move pointer back one item
sqzlp: mvi m,'$' ; Stop on end of string
inx d ; Increment input pointer
ldax d ; Grab character from input string
cmp m ; End reached?
rz ; Then stop
cmp c ; Was it equal to the character to squeeze?
jnz sqzwr ; If not, then write it to the output
mov a,b ; If so, is the previous character?
cmp c
jz sqzlp ; If so, ignore this one
sqzwr: ldax d ; Retrieve the character again
mov m,a ; It goes in the output
mov b,a ; And it is the last character seen
inx h ; Increment output pointer
jmp sqzlp
;;; Print the string in DE and character in C as specified,
;;; squeeze the string and print the output.
prsqz: push b ; Save input parameters
push d
mov a,c ; Store character
sta chval
lxi d,chstr ; Print character
mvi c,puts
call 5
pop h ; Retrieve input string pointer
push h
call prbrkt ; Print the string in brackets
pop d ; Retrieve both input parameters
pop b
lxi h,buffer
call squeez ; Squeeze the input string
lxi h,buffer ; ... fall through to print the result
;;; Write the string at HL and its length in brackets
prbrkt: push h ; Keep the pointer
mvi b,0FFh ; Find the length
mvi a,'$' ; End marker
dcx h
lscan: inr b ; Scan through the string incrementing B
inx h ; and HL until the end is found
cmp m
jnz lscan
mov a,b ; Find high and low digit (assuming < 100)
mvi b,'0'-1
pdigit: inr b ; B = high digit
sui 10
jnc pdigit
lxi h,bstart+1
adi '0'+10
mov m,a ; Write low digit
dcx h
mov m,b ; Write high digit
xchg
mvi c,puts ; Print length and brackets
call 5
pop d ; Retrieve the string pointer
mvi c,puts ; Print the string
call 5
lxi d,bend ; Print the ending brackets
mvi c,puts
jmp 5
;;; Squeeze each string by the given character
demo: lxi h,list ; Pointer to start of list
loop: mov e,m ; Load pointer and character
inx h
mov d,m
inx h
mov c,m
inx h
xra a ; Stop when zero reached
ora c
rz
push h ; Keep list pointer
call prsqz ; Squeeze and print
pop h ; Restore list pointer
jmp loop
;;; Formatting strings
chstr: db 'Character: "'
chval: db '*"',13,10,'$'
bstart: db '##<<<$'
bend: db '>>>'
nl: db 13,10,'$'
;;; Input strings
str1: db '$'
str2: db '"If I were two-faced, would I be wearing'
db ' this one?" --- Abraham Lincoln $'
str3: db '..11111111111111111111111111111111111111'
db '11111111111111111111111117777888$'
str4: db 'I never give ',39,'em hell, I just tell the t'
db 'ruth, and they think it',39,'s hell. $'
str5: db ' '
db ' --- Harry S Truman $'
;;; Pairs of string pointers and characters to squeeze
list: dw str1
db ' '
dw str2
db '-'
dw str3
db '7'
dw str4
db '.'
dw str5
db ' '
dw str5
db '-'
dw str5
db 'r'
dw 0
db 0
buffer: equ $</lang>
{{out}}
<pre>Character: " "
00<<<>>>
00<<<>>>
Character: "-"
72<<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
70<<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>
Character: "7"
72<<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
69<<<..1111111111111111111111111111111111111111111111111111111111111117888>>>
Character: "."
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
Character: " "
72<<< --- Harry S Truman >>>
20<<< --- Harry S Truman >>>
Character: "-"
72<<< --- Harry S Truman >>>
70<<< - Harry S Truman >>>
Character: "r"
72<<< --- Harry S Truman >>>
71<<< --- Hary S Truman >>></pre>
=={{header|Ada}}==
=={{header|Ada}}==
<lang Ada>with Ada.Text_IO; use Ada.Text_IO;
<lang Ada>with Ada.Text_IO; use Ada.Text_IO;

Revision as of 11:19, 28 April 2021

Task
Determine if a string is squeezable
You are encouraged to solve this task according to the task description, using any language you may know.

Determine if a character string is   squeezable.

And if so,   squeeze the string   (by removing any number of a   specified   immediately repeated   character).


This task is very similar to the task     Determine if a character string is collapsible     except that only a specified character is   squeezed   instead of any character that is immediately repeated.


If a character string has a specified   immediately repeated   character(s),   the repeated characters are to be deleted (removed),   but not the primary (1st) character(s).


A specified   immediately repeated   character is any specified character that is   immediately   followed by an identical character (or characters).   Another word choice could've been   duplicated character,   but that might have ruled out   (to some readers)   triplicated characters   ···   or more.


{This Rosetta Code task was inspired by a newly introduced   (as of around November 2019)   PL/I   BIF:   squeeze.}


Examples

In the following character string with a specified   immediately repeated   character of   e: 


 The better the 4-wheel drive, the further you'll be from help when ya get stuck!


Only the 2nd   e   is an specified repeated character,   indicated by an underscore (above),   even though they (the characters) appear elsewhere in the character string.


So, after squeezing the string, the result would be: 

 The better the 4-whel drive, the further you'll be from help when ya get stuck!



Another example: In the following character string,   using a specified immediately repeated character   s: 

 headmistressship


The "squeezed" string would be: 

 headmistreship


Task

Write a subroutine/function/procedure/routine···   to locate a   specified immediately repeated   character and   squeeze   (delete)   them from the character string.   The character string can be processed from either direction.


Show all output here, on this page:

  •   the   specified repeated character   (to be searched for and possibly squeezed):
  •   the   original string and its length
  •   the resultant string and its length
  •   the above strings should be "bracketed" with   <<<   and   >>>   (to delineate blanks)
  •   «««Guillemets may be used instead for "bracketing" for the more artistic programmers,   shown used here»»»


Use (at least) the following five strings,   all strings are length seventy-two (characters, including blanks),   except the 1st string: 

                                                                                  immediately
 string                                                                            repeated
 number                                                                            character
                                                                                     ( ↓   a blank,  a minus,  a seven,  a period)
        ╔╗
   1    ║╚═══════════════════════════════════════════════════════════════════════╗    ' '    ◄■■■■■■  a null string  (length zero)
   2    ║"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ║    '-'
   3    ║..1111111111111111111111111111111111111111111111111111111111111117777888║    '7'
   4    ║I never give 'em hell, I just tell the truth, and they think it's hell. ║    '.'
   5    ║                                                    --- Harry S Truman  ║  (below)  ◄■■■■■■  has many repeated blanks
        ╚════════════════════════════════════════════════════════════════════════╝     ↑
                                                                                       │
                                                                                       │
        For the 5th string  (Truman's signature line),  use each of these  specified immediately  repeated characters:
                                  •  a blank
                                  •  a minus
                                  •  a lowercase  r


Note:   there should be seven results shown,   one each for the 1st four strings,   and three results for the 5th string.

Other tasks related to string operations:
Metrics
Counting
Remove/replace
Anagrams/Derangements/shuffling
Find/Search/Determine
Formatting
Song lyrics/poems/Mad Libs/phrases
Tokenize
Sequences



8080 Assembly

<lang 8080asm>puts: equ 9 org 100h jmp demo ;;; Squeeze the string at DE on the character in C. ;;; The result is written starting at HL. squeez: mvi b,'$' ; Last character seen dcx d ; Move pointer back one item sqzlp: mvi m,'$' ; Stop on end of string inx d ; Increment input pointer ldax d ; Grab character from input string cmp m ; End reached? rz ; Then stop cmp c ; Was it equal to the character to squeeze? jnz sqzwr ; If not, then write it to the output mov a,b ; If so, is the previous character? cmp c jz sqzlp ; If so, ignore this one sqzwr: ldax d ; Retrieve the character again mov m,a ; It goes in the output mov b,a ; And it is the last character seen inx h ; Increment output pointer jmp sqzlp ;;; Print the string in DE and character in C as specified, ;;; squeeze the string and print the output. prsqz: push b ; Save input parameters push d mov a,c ; Store character sta chval lxi d,chstr ; Print character mvi c,puts call 5 pop h ; Retrieve input string pointer push h call prbrkt ; Print the string in brackets pop d ; Retrieve both input parameters pop b lxi h,buffer call squeez ; Squeeze the input string lxi h,buffer ; ... fall through to print the result ;;; Write the string at HL and its length in brackets prbrkt: push h ; Keep the pointer mvi b,0FFh ; Find the length mvi a,'$' ; End marker dcx h lscan: inr b ; Scan through the string incrementing B inx h ; and HL until the end is found cmp m jnz lscan mov a,b ; Find high and low digit (assuming < 100) mvi b,'0'-1 pdigit: inr b ; B = high digit sui 10 jnc pdigit lxi h,bstart+1 adi '0'+10 mov m,a ; Write low digit dcx h mov m,b ; Write high digit xchg mvi c,puts ; Print length and brackets call 5 pop d ; Retrieve the string pointer mvi c,puts ; Print the string call 5 lxi d,bend ; Print the ending brackets mvi c,puts jmp 5 ;;; Squeeze each string by the given character demo: lxi h,list ; Pointer to start of list loop: mov e,m ; Load pointer and character inx h mov d,m inx h mov c,m inx h xra a ; Stop when zero reached ora c rz push h ; Keep list pointer call prsqz ; Squeeze and print pop h ; Restore list pointer jmp loop ;;; Formatting strings chstr: db 'Character: "' chval: db '*"',13,10,'$' bstart: db '##<<<$' bend: db '>>>' nl: db 13,10,'$' ;;; Input strings str1: db '$' str2: db '"If I were two-faced, would I be wearing' db ' this one?" --- Abraham Lincoln $' str3: db '..11111111111111111111111111111111111111' db '11111111111111111111111117777888$' str4: db 'I never give ',39,'em hell, I just tell the t' db 'ruth, and they think it',39,'s hell. $' str5: db ' ' db ' --- Harry S Truman $' ;;; Pairs of string pointers and characters to squeeze list: dw str1 db ' ' dw str2 db '-' dw str3 db '7' dw str4 db '.' dw str5 db ' ' dw str5 db '-' dw str5 db 'r' dw 0 db 0 buffer: equ $</lang>

Output:
Character: " "
00<<<>>>
00<<<>>>
Character: "-"
72<<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
70<<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>
Character: "7"
72<<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
69<<<..1111111111111111111111111111111111111111111111111111111111111117888>>>
Character: "."
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
Character: " "
72<<<                                                    --- Harry S Truman  >>>
20<<< --- Harry S Truman >>>
Character: "-"
72<<<                                                    --- Harry S Truman  >>>
70<<<                                                    - Harry S Truman  >>>
Character: "r"
72<<<                                                    --- Harry S Truman  >>>
71<<<                                                    --- Hary S Truman  >>>

Ada

<lang Ada>with Ada.Text_IO; use Ada.Text_IO; procedure Test_Squeezable is 

  procedure Squeeze (S : in String; C : in Character) is
     Res : String (1 .. S'Length);
     Len : Natural := 0;
  begin
     Put_Line ("Character to be squeezed: '" & C & "'");
     Put_Line ("Input  = <<<" & S & ">>>, length =" & S'Length'Image);
     for I in S'Range loop
        if Len = 0 or else (S(I) /= Res(Len) or S(I) /= C) then
           Len := Len + 1;
           Res(Len) := S(I);
        end if;
     end loop;
     Put_Line ("Output = <<<" & Res (1 .. Len) & ">>>, length =" & Len'Image);
  end Squeeze;

begin 

  Squeeze ("", ' ');
  Squeeze ("""If I were two-faced, would I be wearing this one?"" --- Abraham Lincoln ", '-');
  Squeeze ("..1111111111111111111111111111111111111111111111111111111111111117777888", '7');
  Squeeze ("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.');
  Squeeze ("                                                    --- Harry S Truman  ", ' ');
  Squeeze ("                                                    --- Harry S Truman  ", '-');
  Squeeze ("                                                    --- Harry S Truman  ", 'r');

end Test_Squeezable; </lang>

Output:
Character to be squeezed: ' '
Input  = <<<>>>, length = 0
Output = <<<>>>, length = 0
Character to be squeezed: '-'
Input  = <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>, length = 72
Output = <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>, length = 70
Character to be squeezed: '7'
Input  = <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>, length = 72
Output = <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>, length = 69
Character to be squeezed: '.'
Input  = <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72
Output = <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72
Character to be squeezed: ' '
Input  = <<<                                                    --- Harry S Truman  >>>, length = 72
Output = <<< --- Harry S Truman >>>, length = 20
Character to be squeezed: '-'
Input  = <<<                                                    --- Harry S Truman  >>>, length = 72
Output = <<<                                                    - Harry S Truman  >>>, length = 70
Character to be squeezed: 'r'
Input  = <<<                                                    --- Harry S Truman  >>>, length = 72
Output = <<<                                                    --- Hary S Truman  >>>, length = 71

ALGOL 68

<lang algol68>BEGIN 

   # returns a squeezed version of s                                     #
   #         i.e. s with adjacent duplicate c characters removed         #
   PRIO SQUEEZE = 9;
   OP   SQUEEZE = ( STRING s, CHAR c )STRING:
        IF s = ""
        THEN ""   # empty string                                         #
        ELSE      # non-empty string                                     #
           [ LWB s : UPB s ]CHAR result;
           INT     r pos   := LWB result;
           result[ r pos ] := s[ LWB s ];
           FOR s pos FROM LWB s + 1 TO UPB s DO
               IF  result[ r pos ] /= s[ s pos ]
               OR  result[ r pos ] /= c
               THEN
                   r pos +:= 1;
                   result[ r pos ] := s[ s pos ]
               FI
           OD;
           result[ LWB result : r pos ]
        FI # SQUEEZE # ;
   # test the SQUEEZE operator                                           #
   PROC test squeeze = ( STRING s, CHAR c )VOID:
       BEGIN
           STRING z = s SQUEEZE c;
           print( ( "Squeezing """, c, """ in ", "<<<", s, ">>> (length ", whole( ( UPB s + 1 ) - LWB s, 0 ), ")", newline ) );
           print( ( "       ->        ",         "<<<", z, ">>> (length ", whole( ( UPB z + 1 ) - LWB z, 0 ), ")", newline ) )
       END # test squeeze # ;
   # task test cases                                                     #
   test squeeze( "",                                                                           " " );
   test squeeze( """If I were two-faced, would I be wearing this one?"" --- Abraham Lincoln ", "-" );
   test squeeze( "..1111111111111111111111111111111111111111111111111111111111111117777888",   "7" );
   test squeeze( "I never give 'em hell, I just tell the truth, and they think it's hell. ",   "." );
   STRING hst =  "                                                    --- Harry S Truman  ";
   test squeeze( hst, " " );
   test squeeze( hst, "-" );
   test squeeze( hst, "r" )

END</lang>

Output:
Squeezing " " in <<<>>> (length 0)
       ->        <<<>>> (length 0)
Squeezing "-" in <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>> (length 72)
       ->        <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>> (length 70)
Squeezing "7" in <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>> (length 72)
       ->        <<<..1111111111111111111111111111111111111111111111111111111111111117888>>> (length 69)
Squeezing "." in <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (length 72)
       ->        <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (length 72)
Squeezing " " in <<<                                                    --- Harry S Truman  >>> (length 72)
       ->        <<< --- Harry S Truman >>> (length 20)
Squeezing "-" in <<<                                                    --- Harry S Truman  >>> (length 72)
       ->        <<<                                                    - Harry S Truman  >>> (length 70)
Squeezing "r" in <<<                                                    --- Harry S Truman  >>> (length 72)
       ->        <<<                                                    --- Hary S Truman  >>> (length 71)

APL

Works with: Dyalog APL

<lang APL>task←{ 

   ⍝ Squeeze a string
   squeeze ← ⊢(/⍨)≠∨1,1↓⊣≠¯1⌽⊢

   ⍝ Display string and length in the manner given in the task
   display ← {(¯2↑⍕≢⍵),' «««',⍵,'»»»'}

   ⍝ Squeeze string and display output
   show ← {
       r←  ⊂'chr: ,⍺,'
       r←r,⊂' in: ',display ⍵
       r←r,⊂'out: ',display ⍺ squeeze ⍵
       ↑r,⊂
   }

   ⍝ Strings from the task
   s1←
   s2←'"If I were two-faced, would I be wearing this one?"'
   s2←s2,' --- Abraham Lincoln '
   s3←'..1111111111111111111111111111111111111111111111111'
   s3←s3,'111111111111117777888'
   s4←'I never give em hell, I just tell the truth, and t'
   s4←s4,'hey think its hell. '
   s5←'                                                   '
   s5←s5,' --- Harry S Truman  '

   ⎕←' ' show s1
   ⎕←'-' show s2
   ⎕←'7' show s3
   ⎕←'.' show s4
   {⎕←⍵ show s5}¨' -r'

}</lang>

Output:
chr: ' '      
 in:  0 «««»»»
out:  0 «««»»»
              
chr: '-'                                                                              
 in: 72 «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
out: 70 «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»  
                                                                                      
chr: '7'                                                                              
 in: 72 «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
out: 69 «««..1111111111111111111111111111111111111111111111111111111111111117888»»»   
                                                                                      
chr: '.'                                                                              
 in: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
out: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
                                                                                      
chr: ' '                                                                              
 in: 72 «««                                                    --- Harry S Truman  »»»
out: 20 ««« --- Harry S Truman »»»                                                    
                                                                                      
chr: '-'                                                                              
 in: 72 «««                                                    --- Harry S Truman  »»»
out: 70 «««                                                    - Harry S Truman  »»»  
                                                                                      
chr: 'r'                                                                              
 in: 72 «««                                                    --- Harry S Truman  »»»
out: 71 «««                                                    --- Hary S Truman  »»»

AutoHotkey

<lang AutoHotkey>squeezable_string(str, char){ 

   for i, ch in StrSplit(str){
       if (ch <> prev) || !InStr(ch, char)
           res .= ch
       prev := ch
   }
   result := "
   (ltrim
   Original string:`t" StrLen(str) " characters`t«««" str "»»»
   Squeezable Character «««" char "»»»
   Resultant string:`t" StrLen(res) " characters`t«««" res "»»»
   )"
   return result

}</lang> Examples:<lang AutoHotkey>data := ["" 

   , """If I were two-faced, would I be wearing this one?"" --- Abraham Lincoln "
   , "..1111111111111111111111111111111111111111111111111111111111111117777888"
   , "I never give 'em hell, I just tell the truth, and they think it's hell. "]

char := ["","-","7","."] for i, str in data 

   MsgBox % squeezable_string(str, char[i])

str := " --- Harry S Truman " for i, char in [" ","-","r"] 

   MsgBox % squeezable_string(str, char)

return</lang>

Outputs:

---------------------------
Original string:    0 characters    «««»»»
Squeezable Character «««»»»
Resultant string:   0 characters    «««»»»
---------------------------
Original string:    72 characters   «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
Squeezable Character «««-»»»
Resultant string:   70 characters   «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»
---------------------------
Original string:    72 characters   «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
Squeezable Character «««7»»»
Resultant string:   69 characters   «««..1111111111111111111111111111111111111111111111111111111111111117888»»»
---------------------------
Original string:    72 characters   «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
Squeezable Character «««.»»»
Resultant string:   72 characters   «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
---------------------------
Original string:    72 characters   «««                                                    --- Harry S Truman  »»»
Squeezable Character ««« »»»
Resultant string:   20 characters   ««« --- Harry S Truman »»»
---------------------------
Original string:    72 characters   «««                                                    --- Harry S Truman  »»»
Squeezable Character «««-»»»
Resultant string:   70 characters   «««                                                    - Harry S Truman  »»»
---------------------------
Original string:    72 characters   «««                                                    --- Harry S Truman  »»»
Squeezable Character «««r»»»
Resultant string:   71 characters   «««                                                    --- Hary S Truman  »»»
---------------------------

AWK

<lang AWK>

  1. syntax: GAWK -f DETERMINE_IF_A_STRING_IS_SQUEEZABLE.AWK

BEGIN { 

   arr[++n] = ""                                                                                 ; arr2[n] = " "
   arr[++n] = "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "       ; arr2[n] = "-"
   arr[++n] = "..1111111111111111111111111111111111111111111111111111111111111117777888"         ; arr2[n] = "7"
   arr[++n] = "I never give 'em hell, I just tell the truth, and they think it's hell. "         ; arr2[n] = "."
   arr[++n] = "                                                    --- Harry S Truman  "         ; arr2[n] = " -r"
   arr[++n] = "The better the 4-wheel drive, the further you'll be from help when ya get stuck!" ; arr2[n] = "e"
   arr[++n] = "headmistressship"                                                                 ; arr2[n] = "s"
   for (i=1; i<=n; i++) {
     for (j=1; j<=length(arr2[i]); j++) {
       main(arr[i],substr(arr2[i],j,1))
     }
   }
   exit(0)

} function main(str,chr, c,i,new_str,prev_c) { 

   for (i=1; i<=length(str); i++) {
     c = substr(str,i,1)
     if (!(prev_c == c && c == chr)) {
       prev_c = c
       new_str = new_str c
     }
   }
   printf("use: '%s'\n",chr)
   printf("old: %2d <<<%s>>>\n",length(str),str)
   printf("new: %2d <<<%s>>>\n\n",length(new_str),new_str)

} </lang>

Output:
use: ' '
old:  0 <<<>>>
new:  0 <<<>>>

use: '-'
old: 72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
new: 70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

use: '7'
old: 72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
new: 69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

use: '.'
old: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
new: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

use: ' '
old: 72 <<<                                                    --- Harry S Truman  >>>
new: 20 <<< --- Harry S Truman >>>

use: '-'
old: 72 <<<                                                    --- Harry S Truman  >>>
new: 70 <<<                                                    - Harry S Truman  >>>

use: 'r'
old: 72 <<<                                                    --- Harry S Truman  >>>
new: 71 <<<                                                    --- Hary S Truman  >>>

use: 'e'
old: 80 <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>>
new: 79 <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>>

use: 's'
old: 16 <<<headmistressship>>>
new: 14 <<<headmistreship>>>

BASIC

<lang BASIC>10 DEFINT A-Z 20 READ N: DIM S$(N): FOR I=1 TO N: READ S$(I): NEXT 30 READ S,C$: IF S=0 THEN END 40 PRINT "Character: '";C$;"'" 50 O$=S$(S): GOSUB 200 60 I$=S$(S): GOSUB 100: GOSUB 200 70 PRINT 80 GOTO 30 100 REM -- 101 REM -- Squeeze I$ on character C$, output in O$ 102 REM -- 105 O$ = "" 110 X = INSTR(I$,C$) 120 IF X = 0 THEN O$ = O$ + I$: RETURN 130 O$ = O$ + LEFT$(I$,X) 140 FOR X=X TO LEN(I$): IF MID$(I$,X,1) = C$ THEN NEXT 150 I$ = RIGHT$(I$,LEN(I$)-X+1) 160 GOTO 110 200 REM -- 201 REM -- Display O$ and its length in brackets 202 REM -- 210 PRINT USING "##";LEN(O$); 220 PRINT "<<<";O$;">>>" 230 RETURN 400 REM -- Strings 410 DATA 5 415 DATA"" 420 DATA"'If I were two-faced, would I be wearing this one?' --- Abraham Lincoln " 430 DATA"..1111111111111111111111111111111111111111111111111111111111111117777888" 440 DATA"I never give 'em hell, I just tell the truth, and they think it's hell. " 450 DATA" --- Harry S Truman " 500 REM -- String index and character to squeeze 510 DATA 1," ", 2,"-", 3,"7", 4,".", 5," ", 5,"-", 5,"r", 0,""</lang>

Output:
Character: ' '
 0<<<>>>
 0<<<>>>

Character: '-'
72<<<'If I were two-faced, would I be wearing this one?' --- Abraham Lincoln >>>
70<<<'If I were two-faced, would I be wearing this one?' - Abraham Lincoln >>>

Character: '7'
72<<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
69<<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

Character: '.'
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
72<<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

Character: ' '
72<<<                                                    --- Harry S Truman  >>>
20<<< --- Harry S Truman >>>

Character: '-'
72<<<                                                    --- Harry S Truman  >>>
70<<<                                                    - Harry S Truman  >>>

Character: 'r'
72<<<                                                    --- Harry S Truman  >>>
71<<<                                                    --- Hary S Truman  >>>

C

Identical implementation as in Determine_if_a_string_is_collapsible, as both tasks are very similar. The Lincoln quote contains backslashes to accommodate the double quotes via the command line. strcmpi is not part of the C Standard Library, thus comment out the definition in the code if testing on a system where it is already included. <lang C>

  1. include<string.h>
  2. include<stdlib.h>
  3. include<stdio.h>
  1. define COLLAPSE 0
  2. define SQUEEZE 1

typedef struct charList{ 

   char c;
   struct charList *next;

} charList;

/* Implementing strcmpi, the case insensitive string comparator, as it is not part of the C Standard Library.

Comment this out if testing on a compiler where it is already defined.

  • /

int strcmpi(char str1[100],char str2[100]){ 

   int len1 = strlen(str1), len2 = strlen(str2), i;

   if(len1!=len2){
       return 1;
   }

   else{
       for(i=0;i<len1;i++){
           if((str1[i]>='A'&&str1[i]<='Z')&&(str2[i]>='a'&&str2[i]<='z')&&(str2[i]-65!=str1[i]))
               return 1;
           else if((str2[i]>='A'&&str2[i]<='Z')&&(str1[i]>='a'&&str1[i]<='z')&&(str1[i]-65!=str2[i]))
               return 1;
           else if(str1[i]!=str2[i])
               return 1;
       }
   }

   return 0;

}

charList *strToCharList(char* str){ 

   int len = strlen(str),i;

   charList *list, *iterator, *nextChar;

   list = (charList*)malloc(sizeof(charList));
   list->c = str[0];
   list->next = NULL;

   iterator = list;

   for(i=1;i<len;i++){
       nextChar = (charList*)malloc(sizeof(charList));
       nextChar->c = str[i];
       nextChar->next = NULL;

       iterator->next = nextChar;
       iterator = nextChar;
   }

   return list;

}

char* charListToString(charList* list){ 

   charList* iterator = list;
   int count = 0,i;
   char* str;

   while(iterator!=NULL){
       count++;
       iterator = iterator->next;
   }

   str = (char*)malloc((count+1)*sizeof(char));
   iterator = list;

   for(i=0;i<count;i++){
       str[i] = iterator->c;
       iterator = iterator->next;
   }

   free(list);
   str[i] = '\0';

   return str;

}

char* processString(char str[100],int operation, char squeezeChar){ 

   charList *strList = strToCharList(str),*iterator = strList, *scout;

   if(operation==SQUEEZE){
       while(iterator!=NULL){
           if(iterator->c==squeezeChar){
               scout = iterator->next;

               while(scout!=NULL && scout->c==squeezeChar){
                       iterator->next = scout->next;
                       scout->next = NULL;
                       free(scout);
                       scout = iterator->next;
               }
           }
           iterator = iterator->next;
       }
   }

   else{
       while(iterator!=NULL && iterator->next!=NULL){
           if(iterator->c == (iterator->next)->c){
               scout = iterator->next;
               squeezeChar = iterator->c;

               while(scout!=NULL && scout->c==squeezeChar){
                       iterator->next = scout->next;
                       scout->next = NULL;
                       free(scout);
                       scout = iterator->next;
               }
           }
           iterator = iterator->next;
       }
   }

   return charListToString(strList);

}

void printResults(char originalString[100], char finalString[100], int operation, char squeezeChar){ 

   if(operation==SQUEEZE){
       printf("Specified Operation : SQUEEZE\nTarget Character : %c",squeezeChar);
   }

   else
       printf("Specified Operation : COLLAPSE");

   printf("\nOriginal %c%c%c%s%c%c%c\nLength : %d",174,174,174,originalString,175,175,175,(int)strlen(originalString));
   printf("\nFinal    %c%c%c%s%c%c%c\nLength : %d\n",174,174,174,finalString,175,175,175,(int)strlen(finalString));

}

int main(int argc, char** argv){ 

   int operation;
   char squeezeChar;

   if(argc<3||argc>4){
       printf("Usage : %s <SQUEEZE|COLLAPSE> <String to be processed> <Character to be squeezed, if operation is SQUEEZE>\n",argv[0]);
       return 0;
   }

   if(strcmpi(argv[1],"SQUEEZE")==0 && argc!=4){
       scanf("Please enter characted to be squeezed : %c",&squeezeChar);
       operation = SQUEEZE;
   }

   else if(argc==4){
       operation = SQUEEZE;
       squeezeChar = argv[3][0];
   }

   else if(strcmpi(argv[1],"COLLAPSE")==0){
       operation = COLLAPSE;
   }

   if(strlen(argv[2])<2){
       printResults(argv[2],argv[2],operation,squeezeChar);
   }

   else{
       printResults(argv[2],processString(argv[2],operation,squeezeChar),operation,squeezeChar);
   }
   
   return 0;

} </lang> Output : 

C:\My Projects\networks>a squeeze "The better the 4-wheel drive, the further you'll be from help when ya get stuck!" t
Specified Operation : SQUEEZE
Target Character : t
Original «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
Length : 80
Final    «««The beter the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
Length : 79

C:\My Projects\networks>a squeeze "The better the 4-wheel drive, the further you'll be from help when ya get stuck!" e
Specified Operation : SQUEEZE
Target Character : e
Original «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
Length : 80
Final    «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»
Length : 79

C:\My Projects\networks>a squeeze "The better the 4-wheel drive, the further you'll be from help when ya get stuck!" l
Specified Operation : SQUEEZE
Target Character : l
Original «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
Length : 80
Final    «««The better the 4-wheel drive, the further you'l be from help when ya get stuck!»»»
Length : 79

C:\My Projects\networks>a squeeze headmistressship s
Specified Operation : SQUEEZE
Target Character : s
Original «««headmistressship»»»
Length : 16
Final    «««headmistreship»»»
Length : 14

C:\My Projects\networks>a squeeze "" ""
Specified Operation : SQUEEZE
Target Character :
Original «««»»»
Length : 0
Final    «««»»»
Length : 0

C:\My Projects\networks>a squeeze "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln" -
Specified Operation : SQUEEZE
Target Character : -
Original «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln»»»
Length : 71
Final    «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln»»»
Length : 69

C:\My Projects\networks>a squeeze ..1111111111111111111111111111111111111111111111111111111111111117777888 7
Specified Operation : SQUEEZE
Target Character : 7
Original «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
Length : 72
Final    «««..1111111111111111111111111111111111111111111111111111111111111117888»»»
Length : 69

C:\My Projects\networks>a squeeze "I never give 'em hell, I just tell the truth, and they think it's hell." .
Specified Operation : SQUEEZE
Target Character : .
Original «««I never give 'em hell, I just tell the truth, and they think it's hell.»»»
Length : 71
Final    «««I never give 'em hell, I just tell the truth, and they think it's hell.»»»
Length : 71

C:\My Projects\networks>a squeeze "                                                   ---  Harry S Truman  " " "
Specified Operation : SQUEEZE
Target Character :
Original «««                                                   ---  Harry S Truman  »»»
Length : 72
Final    ««« --- Harry S Truman »»»
Length : 20

C:\My Projects\networks>a squeeze "                                                   ---  Harry S Truman  " -
Specified Operation : SQUEEZE
Target Character : -
Original «««                                                   ---  Harry S Truman  »»»
Length : 72
Final    «««                                                   -  Harry S Truman  »»»
Length : 70

C:\My Projects\networks>a squeeze "                                                   ---  Harry S Truman  " r
Specified Operation : SQUEEZE
Target Character : r
Original «««                                                   ---  Harry S Truman  »»»
Length : 72
Final    «««                                                   ---  Hary S Truman  »»»
Length : 71

C#

<lang csharp>using System; using static System.Linq.Enumerable;

public class Program { 

   static void Main()
   {
       SqueezeAndPrint("", ' ');
       SqueezeAndPrint("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", '-');
       SqueezeAndPrint("..1111111111111111111111111111111111111111111111111111111111111117777888", '7');
       SqueezeAndPrint("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.');
       string s = "                                                    --- Harry S Truman  ";
       SqueezeAndPrint(s, ' ');
       SqueezeAndPrint(s, '-');
       SqueezeAndPrint(s, 'r');
   }

   static void SqueezeAndPrint(string s, char c) {
       Console.WriteLine($"squeeze: '{c}'");
       Console.WriteLine($"old: {s.Length} «««{s}»»»");
       s = Squeeze(s, c);
       Console.WriteLine($"new: {s.Length} «««{s}»»»");
   }

   static string Squeeze(string s, char c) => string.IsNullOrEmpty(s) ? "" :
       s[0] + new string(Range(1, s.Length - 1).Where(i => s[i] != c || s[i] != s[i - 1]).Select(i => s[i]).ToArray());

}</lang>

Output:
squeeze: ' '
old: 0 «««»»»
new: 0 «««»»»
squeeze: '-'
old: 72 «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
new: 70 «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»
squeeze: '7'
old: 72 «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
new: 69 «««..1111111111111111111111111111111111111111111111111111111111111117888»»»
squeeze: '.'
old: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
new: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
squeeze: ' '
old: 72 «««                                                    --- Harry S Truman  »»»
new: 20 ««« --- Harry S Truman »»»
squeeze: '-'
old: 72 «««                                                    --- Harry S Truman  »»»
new: 70 «««                                                    - Harry S Truman  »»»
squeeze: 'r'
old: 72 «««                                                    --- Harry S Truman  »»»
new: 71 «««                                                    --- Hary S Truman  »»»

C++

The solution is a straightforward application of the standard library function "unique". <lang cpp>#include <algorithm>

  1. include <string>
  2. include <iostream>

template<typename char_type> std::basic_string<char_type> squeeze(std::basic_string<char_type> str, char_type ch) { 

   auto i = std::unique(str.begin(), str.end(),
       [ch](char_type a, char_type b) { return a == ch && b == ch; });
   str.erase(i, str.end());
   return str;

}

void test(const std::string& str, char ch) { 

   std::cout << "character: '" << ch << "'\n";
   std::cout << "original: <<<" << str << ">>>, length: " << str.length() << '\n';
   std::string squeezed(squeeze(str, ch));
   std::cout << "result: <<<" << squeezed << ">>>, length: " << squeezed.length() << '\n';
   std::cout << '\n';

}

int main(int argc, char** argv) { 

   test("", ' ');
   test("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", '-');
   test("..1111111111111111111111111111111111111111111111111111111111111117777888", '7');
   test("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.');
   std::string truman("                                                    --- Harry S Truman  ");
   test(truman, ' ');
   test(truman, '-');
   test(truman, 'r');
   return 0;

}</lang>

Output:
character: ' '
original: <<<>>>, length: 0
result: <<<>>>, length: 0

character: '-'
original: <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>, length: 72
result: <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>, length: 70

character: '7'
original: <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>, length: 72
result: <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>, length: 69

character: '.'
original: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length: 72
result: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length: 72

character: ' '
original: <<<                                                    --- Harry S Truman  >>>, length: 72
result: <<< --- Harry S Truman >>>, length: 20

character: '-'
original: <<<                                                    --- Harry S Truman  >>>, length: 72
result: <<<                                                    - Harry S Truman  >>>, length: 70

character: 'r'
original: <<<                                                    --- Harry S Truman  >>>, length: 72
result: <<<                                                    --- Hary S Truman  >>>, length: 71

Clojure

<lang Clojure> (defn squeeze [s c] 

 (let [spans (partition-by #(= c %) s)
       span-out (fn [span]
                  (if (= c (first span))
                    (str c)
                    (apply str span)))]
   (apply str (map span-out spans))))

(defn test-squeeze [s c] 

 (let [out (squeeze s c)]
   (println (format "Input:   <<<%s>>> (len %d)\n" s (count s))
            (format "becomes: <<<%s>>> (len %d)" out (count out)))))

</lang>

Output:
(def test-data [""
                "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "
                "..1111111111111111111111111111111111111111111111111111111111111117777888"
                "I never give 'em hell, I just tell the truth, and they think it's hell. "
                "                                                    --- Harry S Truman  "])

(test-squeeze (nth test-data 0) (first " "))
  Input:   <<<>>> (len 0)
  becomes: <<<>>> (len 0)
(test-squeeze (nth test-data 1) \-)
  Input:   <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>> (len 72)
  becomes: <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>> (len 70)
(test-squeeze (nth test-data 2) \7)
  Input:   <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>> (len 72)
  becomes: <<<..1111111111111111111111111111111111111111111111111111111111111117888>>> (len 69)
(test-squeeze (nth test-data 3) \.)
  Input:   <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (len 72)
  becomes: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (len 72)
(test-squeeze (nth test-data 4) (first " "))
  Input:   <<<                                                    --- Harry S Truman  >>> (len 72)
  becomes: <<< --- Harry S Truman >>> (len 20)
(test-squeeze (nth test-data 4) \-)
  Input:   <<<                                                    --- Harry S Truman  >>> (len 72)
  becomes: <<<                                                    - Harry S Truman  >>> (len 70)
(test-squeeze (nth test-data 4) \r)
  Input:   <<<                                                    --- Harry S Truman  >>> (len 72)
  becomes: <<<                                                    --- Hary S Truman  >>> (len 71)

Cowgol

<lang cowgol>include "cowgol.coh"; include "strings.coh";

sub squeeze(ch: uint8, str: [uint8], buf: [uint8]): (r: [uint8]) is 

   r := buf;
   var prev: uint8 := 0;
   while [str] != 0 loop
       if prev != ch or [str] != ch then
           prev := [str];
           [buf] := prev;
           buf := @next buf;
       end if;
       str := @next str;
   end loop;
   [buf] := 0;

end sub;

sub squeezeAndPrint(ch: uint8, str: [uint8]) is 

   sub bracketLength(str: [uint8]) is
       print_i32(StrLen(str) as uint32);
       print(" <<<");
       print(str);
       print(">>>\n");
   end sub;
   
   var buf: uint8[256];
   bracketLength(str);
   bracketLength(squeeze(ch, str, &buf[0]));
   print_nl();

end sub;

var strs: [uint8][] := { "", "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", "..1111111111111111111111111111111111111111111111111111111111111117777888", "I never give 'em hell, I just tell the truth, and they think it's hell. ", " --- Harry S Truman " };

squeezeAndPrint(' ', strs[0]); squeezeAndPrint('-', strs[1]); squeezeAndPrint('7', strs[2]); squeezeAndPrint('.', strs[3]); squeezeAndPrint(' ', strs[4]); squeezeAndPrint('-', strs[4]); squeezeAndPrint('r', strs[4]);</lang>

Output:
0 <<<>>>
0 <<<>>>

72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

72 <<<                                                    --- Harry S Truman  >>>
20 <<< --- Harry S Truman >>>

72 <<<                                                    --- Harry S Truman  >>>
70 <<<                                                    - Harry S Truman  >>>

72 <<<                                                    --- Harry S Truman  >>>
71 <<<                                                    --- Hary S Truman  >>>

D

Translation of: C#

<lang d>import std.stdio;

void squeezable(string s, char rune) { 

   writeln("squeeze: '", rune, "'");
   writeln("old: <<<", s, ">>>, length = ", s.length);

   write("new: <<<");
   char last = '\0';
   int len = 0;
   foreach (c; s) {
       if (c != last || c != rune) {
           write(c);
           len++;
       }
       last = c;
   }
   writeln(">>>, length = ", len);

   writeln;

}

void main() { 

   squeezable(``, ' ');
   squeezable(`"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln `, '-');
   squeezable(`..1111111111111111111111111111111111111111111111111111111111111117777888`, '7');
   squeezable(`I never give 'em hell, I just tell the truth, and they think it's hell. `, '.');

   string s = `                                                    --- Harry S Truman  `;
   squeezable(s, ' ');
   squeezable(s, '-');
   squeezable(s, 'r');

}</lang>

Output:
squeeze: ' '
old: <<<>>>, length = 0
new: <<<>>>, length = 0

squeeze: '-'
old: <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>, length = 72
new: <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>, length = 70

squeeze: '7'
old: <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>, length = 72
new: <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>, length = 69

squeeze: '.'
old: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72
new: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72

squeeze: ' '
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<< --- Harry S Truman >>>, length = 20

squeeze: '-'
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<<                                                    - Harry S Truman  >>>, length = 70

squeeze: 'r'
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<<                                                    --- Hary S Truman  >>>, length = 71

Delphi

Library: System.SysUtils
Translation of: Java

<lang Delphi> program Determine_if_a_string_is_squeezable;

{$APPTYPE CONSOLE}

uses 

 System.SysUtils;

var 

 TestStrings: TArray<string> = [,
   'If I were two-faced, would I be wearing this one? --- Abraham Lincoln ',
   '..1111111111111111111111111111111111111111111111111111111111111117777888',
   'I never give em hell, I just tell the truth, and they think its hell. ',
   '                                                    --- Harry S Truman  ',
   '122333444455555666666777777788888888999999999',
   'The better the 4-wheel drive, the further youll be from help when ya get stuck!',
   'headmistressship'];
 TestChar: TArray<string> = [' ', '-', '7', '.', ' -r', '5', 'e', 's'];

function squeeze(s: string; include: char): string; begin 

 var sb := TStringBuilder.Create;
 for var i := 1 to s.Length do
 begin
   if (i = 1) or (s[i - 1] <> s[i]) or ((s[i - 1] = s[i]) and (s[i] <> include)) then
     sb.Append(s[i]);
 end;
 Result := sb.ToString;
 sb.Free;

end;

begin 

 for var testNum := 0 to high(TestStrings) do
 begin
   var s := TestStrings[testNum];
   for var c in TestChar[testNum] do
   begin
     var result: string := squeeze(s, c);
     writeln(format('use: "%s"'#10'old:  %2d <<<%s>>>'#10'new:  %2d <<<%s>>>'#10, [c,
       s.Length, s, result.length, result]));
   end;
 end;
 readln;

end.</lang>

Output:
use: " "
old:   0 <<<>>>
new:   0 <<<>>>

use: "-"
old:  72 <<<'If I were two-faced, would I be wearing this one?' --- Abraham Lincoln >>>
new:  70 <<<'If I were two-faced, would I be wearing this one?' - Abraham Lincoln >>>

use: "7"
old:  72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
new:  69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

use: "."
old:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
new:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

use: " "
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  20 <<< --- Harry S Truman >>>

use: "-"
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  70 <<<                                                    - Harry S Truman  >>>

use: "r"
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  71 <<<                                                    --- Hary S Truman  >>>

use: "5"
old:  45 <<<122333444455555666666777777788888888999999999>>>
new:  41 <<<12233344445666666777777788888888999999999>>>

use: "e"
old:  80 <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>>
new:  79 <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>>

use: "s"
old:  16 <<<headmistressship>>>
new:  14 <<<headmistreship>>>

F#

<lang fsharp> // Determine if a string is squeezable. Nigel Galloway: June 9th., 2020 let squeeze n i=if String.length n=0 then None else 

               let fN=let mutable g=n.[0] in (fun n->if n=i && n=g then false else g<-n; true)
               let fG=n.[0..0]+System.String(n.[1..].ToCharArray()|>Array.filter fN)
               if fG.Length=n.Length then None else Some fG

let isSqueezable n g=match squeeze n g with 

                     Some i->printfn "%A squeezes <<<%s>>> (length %d) to <<<%s>>> (length %d)" g n n.Length i i.Length
                    |_->printfn "%A does not squeeze <<<%s>>> (length %d)" g n n.Length

isSqueezable "" ' ' isSqueezable "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln " '-' isSqueezable "..1111111111111111111111111111111111111111111111111111111111111117777888" '7' isSqueezable "I never give 'em hell, I just tell the truth, and they think it's hell. " '.' let fN=isSqueezable " --- Harry S Truman " in fN ' '; fN '-'; fN 'r' </lang>

Output:
' ' does not squeeze <<<>>> (length 0)
'-' squeezes <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>> (length 72) to <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>> (length 70)
'7' squeezes <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>> (length 72) to <<<..1111111111111111111111111111111111111111111111111111111111111117888>>> (length 69)
'.' does not squeeze <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (length 72)
' ' squeezes <<<                                                    --- Harry S Truman  >>> (length 72) to <<< --- Harry S Truman >>> (length 20)
'-' squeezes <<<                                                    --- Harry S Truman  >>> (length 72) to <<<                                                    - Harry S Truman  >>> (length 70)
'r' squeezes <<<                                                    --- Harry S Truman  >>> (length 72) to <<<                                                    --- Hary S Truman  >>> (length 71)

Factor

<lang factor>USING: formatting fry io kernel math sbufs sequences strings ; IN: rosetta-code.squeeze

(squeeze) ( str c -- new-str )
   [ unclip-slice 1string >sbuf ] dip
   '[ over last over [ _ = ] both? [ drop ] [ suffix! ] if ]
   reduce >string ;
squeeze ( str c -- new-str )
   over empty? [ 2drop "" ] [ (squeeze) ] if ;
.str ( str -- ) dup length "«««%s»»» (length %d)\n" printf ;
show-squeeze ( str c -- )
   dup "Specified character: '%c'\n" printf
   [ "Before squeeze: " write drop .str ]
   [ "After  squeeze: " write squeeze .str ] 2bi nl ;
squeeze-demo ( -- )
   {
       ""
       "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "
       "..1111111111111111111111111111111111111111111111111111111111111117777888"
       "I never give 'em hell, I just tell the truth, and they think it's hell. "
   } "\0-7." [ show-squeeze ] 2each

   "                                                   ---  Harry S Truman  "
   [ CHAR: space ] [ CHAR: - ] [ CHAR: r ] tri
   [ show-squeeze ] 2tri@ ;

MAIN: squeeze-demo</lang>

Output:
Specified character: ' '
Before squeeze: «««»»» (length 0)
After  squeeze: «««»»» (length 0)

Specified character: '-'
Before squeeze: «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»» (length 72)
After  squeeze: «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»» (length 70)

Specified character: '7'
Before squeeze: «««..1111111111111111111111111111111111111111111111111111111111111117777888»»» (length 72)
After  squeeze: «««..1111111111111111111111111111111111111111111111111111111111111117888»»» (length 69)

Specified character: '.'
Before squeeze: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length 72)
After  squeeze: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length 72)

Specified character: ' '
Before squeeze: «««                                                   ---  Harry S Truman  »»» (length 72)
After  squeeze: ««« --- Harry S Truman »»» (length 20)

Specified character: '-'
Before squeeze: «««                                                   ---  Harry S Truman  »»» (length 72)
After  squeeze: «««                                                   -  Harry S Truman  »»» (length 70)

Specified character: 'r'
Before squeeze: «««                                                   ---  Harry S Truman  »»» (length 72)
After  squeeze: «««                                                   ---  Hary S Truman  »»» (length 71)

Go

<lang go>package main

import "fmt"

// Returns squeezed string, original and new lengths in // unicode code points (not normalized). func squeeze(s string, c rune) (string, int, int) { 

   r := []rune(s)
   le, del := len(r), 0
   for i := le - 2; i >= 0; i-- {
       if r[i] == c && r[i] == r[i+1] {
           copy(r[i:], r[i+1:])
           del++
       }
   }
   if del == 0 {
       return s, le, le
   }
   r = r[:le-del]
   return string(r), le, len(r)

}

func main() { 

   strings := []string{
       "",
       `"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln `,
       "..1111111111111111111111111111111111111111111111111111111111111117777888",
       "I never give 'em hell, I just tell the truth, and they think it's hell. ",
       "                                                   ---  Harry S Truman  ",
       "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
       "headmistressship",
       "aardvark",
       "😍😀🙌💃😍😍😍🙌",
   }
   chars := [][]rune{{' '}, {'-'}, {'7'}, {'.'}, {' ', '-', 'r'}, {'e'}, {'s'}, {'a'}, {'😍'}}

   for i, s := range strings {
       for _, c := range chars[i] {
           ss, olen, slen := squeeze(s, c)
           fmt.Printf("specified character = %q\n", c)
           fmt.Printf("original : length = %2d, string = «««%s»»»\n", olen, s)
           fmt.Printf("squeezed : length = %2d, string = «««%s»»»\n\n", slen, ss)
       }
   }

}</lang>

Output:
specified character = ' '
original : length =  0, string = «««»»»
squeezed : length =  0, string = «««»»»

specified character = '-'
original : length = 72, string = «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
squeezed : length = 70, string = «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»

specified character = '7'
original : length = 72, string = «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
squeezed : length = 69, string = «««..1111111111111111111111111111111111111111111111111111111111111117888»»»

specified character = '.'
original : length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
squeezed : length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»

specified character = ' '
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 20, string = ««« --- Harry S Truman »»»

specified character = '-'
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 70, string = «««                                                   -  Harry S Truman  »»»

specified character = 'r'
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 71, string = «««                                                   ---  Hary S Truman  »»»

specified character = 'e'
original : length = 80, string = «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
squeezed : length = 79, string = «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»

specified character = 's'
original : length = 16, string = «««headmistressship»»»
squeezed : length = 14, string = «««headmistreship»»»

specified character = 'a'
original : length =  8, string = «««aardvark»»»
squeezed : length =  7, string = «««ardvark»»»

specified character = '😍'
original : length =  8, string = «««😍😀🙌💃😍😍😍🙌»»»
squeezed : length =  6, string = «««😍😀🙌💃😍🙌»»»

Groovy

Translation of: Java

<lang groovy>class StringSqueezable { 

   static void main(String[] args) {
       String[] testStrings = [
               "",
               "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ",
               "..1111111111111111111111111111111111111111111111111111111111111117777888",
               "I never give 'em hell, I just tell the truth, and they think it's hell. ",
               "                                                    --- Harry S Truman  ",
               "122333444455555666666777777788888888999999999",
               "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
               "headmistressship"
       ]

       String[] testChar = [" ", "-", "7", ".", " -r", "5", "e", "s"]
       for (int testNum = 0; testNum < testStrings.length; testNum++) {
           String s = testStrings[testNum]
           for (char c : testChar[testNum].toCharArray()) {
               String result = squeeze(s, c)
               System.out.printf("use: '%c'%nold:  %2d <<<%s>>>%nnew:  %2d <<<%s>>>%n%n", c, s.length(), s, result.length(), result)
           }
       }
   }

   private static String squeeze(String input, char include) {
       StringBuilder sb = new StringBuilder()
       for (int i = 0; i < input.length(); i++) {
           if (i == 0 || input.charAt(i - 1) != input.charAt(i) || (input.charAt(i - 1) == input.charAt(i) && input.charAt(i) != include)) {
               sb.append(input.charAt(i))
           }
       }
       return sb.toString()
   }

}</lang>

Output:
use: ' '
old:   0 <<<>>>
new:   0 <<<>>>

use: '-'
old:  72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
new:  70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

use: '7'
old:  72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
new:  69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

use: '.'
old:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
new:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

use: ' '
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  20 <<< --- Harry S Truman >>>

use: '-'
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  70 <<<                                                    - Harry S Truman  >>>

use: 'r'
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  71 <<<                                                    --- Hary S Truman  >>>

use: '5'
old:  45 <<<122333444455555666666777777788888888999999999>>>
new:  41 <<<12233344445666666777777788888888999999999>>>

use: 'e'
old:  80 <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>>
new:  79 <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>>

use: 's'
old:  16 <<<headmistressship>>>
new:  14 <<<headmistreship>>>

Haskell

<lang haskell>import Text.Printf (printf)

input :: [(String, Char)] input = [ ("", ' ') 

       , ("The better the 4-wheel drive, the further you'll be from help when ya get stuck!", 'e')
       , ("headmistressship", 's')
       , ("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", '-')
       , ("..1111111111111111111111111111111111111111111111111111111111111117777888", '7')
       , ("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.')
       , ("                                                    --- Harry S Truman  ", 'r')
       , ("aardvark", 'a')
       , ("😍😀🙌💃😍😍😍🙌", '😍')
       ]

collapse :: Eq a => [a] -> a -> [a] collapse s c = go s 

 where go [] = []
       go (x:y:xs)
         | x == y && x == c = go (y:xs)
         | otherwise        = x : go (y:xs)
       go xs = xs

main :: IO () main = 

 mapM_ (\(a, b, c) -> printf "squeeze: '%c'\nold: %3d «««%s»»»\nnew: %3d «««%s»»»\n\n" c (length a) a (length b) b) 
 $ (\(s, c) -> (s, collapse s c, c)) <$> input</lang>
Output:
squeeze: ' '
old:   0 «««»»»
new:   0 «««»»»

squeeze: 'e'
old:  80 «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
new:  79 «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»

squeeze: 's'
old:  16 «««headmistressship»»»
new:  14 «««headmistreship»»»

squeeze: '-'
old:  72 «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
new:  70 «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»

squeeze: '7'
old:  72 «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
new:  69 «««..1111111111111111111111111111111111111111111111111111111111111117888»»»

squeeze: '.'
old:  72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
new:  72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»

squeeze: 'r'
old:  72 «««                                                    --- Harry S Truman  »»»
new:  71 «««                                                    --- Hary S Truman  »»»

squeeze: 'a'
old:   8 «««aardvark»»»
new:   7 «««ardvark»»»

squeeze: '😍'
old:   8 «««😍😀🙌💃😍😍😍🙌»»»
new:   6 «««😍😀🙌💃😍🙌»»»

J

Invoking j with the standard startup scripts includes definitions to delete excess, leading, and trailing blanks. deb corresponds to task squeeze, additionally removing leading and trailing blanks. The definitions are <lang j> 

  dlb

}.~ (=&' ' (i.) 0:) 

  dtb
  1. ~ ([: +./\. ' '&~:)
  deb
  1. ~ ((+.) (1: |. (> </\)))@(' '&~:)

</lang> Onward with the task. squeeze makes a logical vector of inequality and uses Boolean algebra against itself shifted by one position to mask the text. 

squeeze=: (] #~ 1 (0}) [: (+. _1&|.) ~:) ::(''"_)

main=: dyad define
 squoze=. x squeeze y
 msg=. ,: 'squeeze ''' , x , ''' reduces the length from ',(":#y),' to ',(":#squoze)
 msg=. msg , '<<<' ,  y , '>>>'
 msg=. msg , '<<<' ,  squoze , '>>>'
)

to_be_squished=: noun define

"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln
..1111111111111111111111111111111111111111111111111111111111111117777888
I never give 'em hell, I just tell the truth, and they think it's hell.
                                                    --- Harry S Truman
                                                    --- Harry S Truman
                                                    --- Harry S Truman
)

<lang J> 

  'x' squeeze 'xabxxcxdxxx'  NB. example

xabxcxdx 


  ,.' -7. -r' main&.> <;._2 to_be_squished

┌──────────────────────────────────────────────────────────────────────────────┐ │squeeze ' ' reduces the length from 0 to 0 │ │<<<>>> │ │<<<>>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze '-' reduces the length from 71 to 69 │ │<<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln>>> │ │<<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln>>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze '7' reduces the length from 72 to 69 │ │<<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>│ │<<<..1111111111111111111111111111111111111111111111111111111111111117888>>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze '.' reduces the length from 71 to 71 │ │<<>> │ │<<>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze ' ' reduces the length from 70 to 19 │ │<<< --- Harry S Truman>>> │ │<<< --- Harry S Truman>>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze '-' reduces the length from 70 to 68 │ │<<< --- Harry S Truman>>> │ │<<< - Harry S Truman>>> │ ├──────────────────────────────────────────────────────────────────────────────┤ │squeeze 'r' reduces the length from 70 to 69 │ │<<< --- Harry S Truman>>> │ │<<< --- Hary S Truman>>> │ └──────────────────────────────────────────────────────────────────────────────┘ </lang>

Java

<lang Java>

// Title: Determine if a string is squeezable

public class StringSqueezable { 

   public static void main(String[] args) {
       String[] testStrings = new String[] {
               "", 
               "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", 
               "..1111111111111111111111111111111111111111111111111111111111111117777888", 
               "I never give 'em hell, I just tell the truth, and they think it's hell. ", 
               "                                                    --- Harry S Truman  ",
               "122333444455555666666777777788888888999999999",
               "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
               "headmistressship"};

       String[] testChar = new String[] {
               " ", 
               "-", 
               "7", 
               ".", 
               " -r",
               "5",
               "e",
               "s"};
       for ( int testNum = 0 ; testNum < testStrings.length ; testNum++ ) {
           String s = testStrings[testNum];
           for ( char c : testChar[testNum].toCharArray() ) {
               String result = squeeze(s, c);
               System.out.printf("use: '%c'%nold:  %2d <<<%s>>>%nnew:  %2d <<<%s>>>%n%n", c, s.length(), s, result.length(), result);
           }
       }
   }
   
   private static String squeeze(String in, char include) {
       StringBuilder sb = new StringBuilder();
       for ( int i = 0 ; i < in.length() ; i++ ) {
           if ( i == 0 || in.charAt(i-1) != in.charAt(i) || (in.charAt(i-1) == in.charAt(i) && in.charAt(i) != include)) {
               sb.append(in.charAt(i));
           }
       }
       return sb.toString();
   }

} </lang>

Output:
use: ' '
old:   0 <<<>>>
new:   0 <<<>>>

use: '-'
old:  72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
new:  70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

use: '7'
old:  72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
new:  69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

use: '.'
old:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
new:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

use: ' '
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  20 <<< --- Harry S Truman >>>

use: '-'
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  70 <<<                                                    - Harry S Truman  >>>

use: 'r'
old:  72 <<<                                                    --- Harry S Truman  >>>
new:  71 <<<                                                    --- Hary S Truman  >>>

use: '5'
old:  45 <<<122333444455555666666777777788888888999999999>>>
new:  41 <<<12233344445666666777777788888888999999999>>>

use: 'e'
old:  80 <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>>
new:  79 <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>>

use: 's'
old:  16 <<<headmistressship>>>
new:  14 <<<headmistreship>>>

jq

Preamble

The PL/I documentation makes it clear that all runs of the specified character are to be squeezed:

  • "SQUEEZE returns a string that reduces all multiple occurrences of a [specified] character to one ..."
  • The example given is in effect 'SabcSS:SSdefSSSghSS' => 'SabcS:SdefSghS' where S signifies a single space character.

jq program

<lang jq># Assume $c is specified as a single character correctly def squeeze($c): gsub("[\($c)]+"; $c);

def Guillemets: "«««\(.)»»»";

def Squeeze(s; $c): 

 "Squeeze character: \($c)",
  (s | "Original: \(Guillemets) has length \(length)",
       (squeeze($c) | "result is \(Guillemets) with length \(length)")),
  "";</lang>

Demo

<lang jq> Squeeze("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "; "-"), 

  Squeeze ("..1111111111111111111111111111111111111111111111111111111111111117777888"; "7"),
  Squeeze ("I never give 'em hell, I just tell the truth, and they think it's hell. "; "."),
  Squeeze ("                                                    --- Harry S Truman  "; " "),
  Squeeze ("                                                    --- Harry S Truman  "; "-"),
  Squeeze ("                                                    --- Harry S Truman  "; "r"),

  Squeeze("SabcSS:SSdefSSSghSS";"S")</lang>
Output:

<lang sh>Squeeze character: - Original: «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»» has length 72 result is «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»» with length 70

Squeeze character: 7 Original: «««..1111111111111111111111111111111111111111111111111111111111111117777888»»» has length 72 result is «««..1111111111111111111111111111111111111111111111111111111111111117888»»» with length 69

Squeeze character: . Original: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» has length 72 result is «««.»»» with length 1

Squeeze character: Original: «««  --- Harry S Truman  »»» has length 72 result is ««« --- Harry S Truman »»» with length 20

Squeeze character: - Original: «««  --- Harry S Truman  »»» has length 72 result is «««  - Harry S Truman  »»» with length 70

Squeeze character: r Original: «««  --- Harry S Truman  »»» has length 72 result is «««  --- Hary S Truman  »»» with length 71

Squeeze character: S Original: «««SabcSS:SSdefSSSghSS»»» has length 19 result is «««SabcS:SdefSghS»»» with length 14</lang>

Julia

<lang julia>const teststringpairs = [ 

   ("", ' '),
   (""""If I were two-faced, would I be wearing this one?" --- Abraham Lincoln """, '-'),
   ("..1111111111111111111111111111111111111111111111111111111111111117777888", '7'),
   ("""I never give 'em hell, I just tell the truth, and they think it's hell. """, '.'),
   ("                                                    --- Harry S Truman  ", ' '),
   ("                                                    --- Harry S Truman  ", '-'),
   ("                                                    --- Harry S Truman  ", 'r')]

function squeezed(s, c) 

   t = isempty(s) ? "" : s[1:1]
   for x in s[2:end]
       if x != t[end] || x != c
           t *= x
       end
   end
   t

end

for (s, c) in teststringpairs 

   n, t = length(s), squeezed(s, c)
   println("«««$s»»» (length $n)\n",
       s == t ? "is not squeezed, so remains" : "squeezes to", 
       ":\n«««$t»»» (length $(length(t))).\n")

end

</lang>

Output:
«««»»» (length 0)
is not squeezed, so remains:
«««»»» (length 0).

«««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»» (length 72)
squeezes to:
«««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»» (length 70).

«««..1111111111111111111111111111111111111111111111111111111111111117777888»»» (length 72)
squeezes to:
«««..1111111111111111111111111111111111111111111111111111111111111117888»»» (length 69).

«««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length 72)
is not squeezed, so remains:
«««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length 72).

«««                                                    --- Harry S Truman  »»» (length 72)
squeezes to:
««« --- Harry S Truman »»» (length 20).

«««                                                    --- Harry S Truman  »»» (length 72)
squeezes to:
«««                                                    - Harry S Truman  »»» (length 70).

«««                                                    --- Harry S Truman  »»» (length 72)
squeezes to:
«««                                                    --- Hary S Truman  »»» (length 71).

Kotlin

Translation of: Java

<lang scala>fun main() { 

   val testStrings = arrayOf(
       "",
       "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ",
       "..1111111111111111111111111111111111111111111111111111111111111117777888",
       "I never give 'em hell, I just tell the truth, and they think it's hell. ",
       "                                                    --- Harry S Truman  ",
       "122333444455555666666777777788888888999999999",
       "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
       "headmistressship")
   val testChar = arrayOf(
       " ",
       "-",
       "7",
       ".",
       " -r",
       "5",
       "e",
       "s")
   for (testNum in testStrings.indices) {
       val s = testStrings[testNum]
       for (c in testChar[testNum].toCharArray()) {
           val result = squeeze(s, c)
           System.out.printf("use: '%c'%nold:  %2d >>>%s<<<%nnew:  %2d >>>%s<<<%n%n", c, s.length, s, result.length, result)
       }
   }

}

private fun squeeze(input: String, include: Char): String { 

   val sb = StringBuilder()
   for (i in input.indices) {
       if (i == 0 || input[i - 1] != input[i] || input[i - 1] == input[i] && input[i] != include) {
           sb.append(input[i])
       }
   }
   return sb.toString()

}</lang>

Output:
use: ' '
old:   0 >>><<<
new:   0 >>><<<

use: '-'
old:  72 >>>"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln <<<
new:  70 >>>"If I were two-faced, would I be wearing this one?" - Abraham Lincoln <<<

use: '7'
old:  72 >>>..1111111111111111111111111111111111111111111111111111111111111117777888<<<
new:  69 >>>..1111111111111111111111111111111111111111111111111111111111111117888<<<

use: '.'
old:  72 >>>I never give 'em hell, I just tell the truth, and they think it's hell. <<<
new:  72 >>>I never give 'em hell, I just tell the truth, and they think it's hell. <<<

use: ' '
old:  72 >>>                                                    --- Harry S Truman  <<<
new:  20 >>> --- Harry S Truman <<<

use: '-'
old:  72 >>>                                                    --- Harry S Truman  <<<
new:  70 >>>                                                    - Harry S Truman  <<<

use: 'r'
old:  72 >>>                                                    --- Harry S Truman  <<<
new:  71 >>>                                                    --- Hary S Truman  <<<

use: '5'
old:  45 >>>122333444455555666666777777788888888999999999<<<
new:  41 >>>12233344445666666777777788888888999999999<<<

use: 'e'
old:  80 >>>The better the 4-wheel drive, the further you'll be from help when ya get stuck!<<<
new:  79 >>>The better the 4-whel drive, the further you'll be from help when ya get stuck!<<<

use: 's'
old:  16 >>>headmistressship<<<
new:  14 >>>headmistreship<<<

Lua

Translation of: D

<lang lua>function squeezable(s, rune) 

   print("squeeze: `" .. rune .. "`")
   print("old: <<<" .. s .. ">>>, length = " .. string.len(s))

   local last = nil
   local le = 0
   io.write("new: <<<")
   for c in s:gmatch"." do
       if c ~= last or c ~= rune then
           io.write(c)
           le = le + 1
       end
       last = c
   end
   print(">>>, length = " .. le)

   print()

end

function main() 

   squeezable("", ' ');
   squeezable("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", '-')
   squeezable("..1111111111111111111111111111111111111111111111111111111111111117777888", '7')
   squeezable("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.')

   local s = "                                                    --- Harry S Truman  "
   squeezable(s, ' ')
   squeezable(s, '-')
   squeezable(s, 'r')

end

main()</lang>

Output:
squeeze: ` `
old: <<<>>>, length = 0
new: <<<>>>, length = 0

squeeze: `-`
old: <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>, length = 72
new: <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>, length = 70

squeeze: `7`
old: <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>, length = 72
new: <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>, length = 69

squeeze: `.`
old: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72
new: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>, length = 72

squeeze: ` `
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<< --- Harry S Truman >>>, length = 20

squeeze: `-`
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<<                                                    - Harry S Truman  >>>, length = 70

squeeze: `r`
old: <<<                                                    --- Harry S Truman  >>>, length = 72
new: <<<                                                    --- Hary S Truman  >>>, length = 71


MATLAB / Octave

squeeze is a base function Matlab and Octave, therefore its name is changed to squeezee()

<lang Matlab> function r = squeezee(s,c) 

 ix = [];
 c  = unique(c);
 for k=1:length(c)
   ix=[ix; find((s(1:end-1)==s(2:end)) & (s(1:end-1)==c(k)))+1];
 end
 r=s;
 r(ix)=[];     

 fprintf(1,'Character to be squeezed: "%s"\n',c);
 fprintf(1,'Input:  <<<%s>>>  length: %d\n',s,length(s));
 fprintf(1,'Output: <<<%s>>>  length: %d\n',r,length(r));
 fprintf(1,'Character to be squeezed: "%s"\n',c);

end


squeezee(, ' ') squeezee('║╚═══════════════════════════════════════════════════════════════════════╗', '-') squeezee('║"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ║', '7') squeezee('║..1111111111111111111111111111111111111111111111111111111111111117777888║', '.') squeezee('║I never give em hell, I just tell the truth, and they think its hell. ║', '.') squeezee('║ --- Harry S Truman ║', '.') squeezee('║ --- Harry S Truman ║', '-') squeezee('║ --- Harry S Truman ║', 'r')

</lang>

Output:
octave:1> test squeezee
Character to be squeezed: " "
Input:  <<<>>>  length: 0
Output: <<<>>>  length: 0
Character to be squeezed: " "
ans =
Character to be squeezed: "-"
Input:  <<<║╚═══════════════════════════════════════════════════════════════════════╗>>>  length: 222
Output: <<<║╚═══════════════════════════════════════════════════════════════════════╗>>>  length: 222
Character to be squeezed: "-"
ans = ║╚═══════════════════════════════════════════════════════════════════════╗
Character to be squeezed: "7"
Input:  <<<║"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ║>>>  length: 78
Output: <<<║"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ║>>>  length: 78
Character to be squeezed: "7"
ans = ║"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ║
Character to be squeezed: "."
Input:  <<<║..1111111111111111111111111111111111111111111111111111111111111117777888║>>>  length: 78
Output: <<<║.1111111111111111111111111111111111111111111111111111111111111117777888║>>>  length: 77
Character to be squeezed: "."
ans = ║.1111111111111111111111111111111111111111111111111111111111111117777888║
Character to be squeezed: "."
Input:  <<<║I never give 'em hell, I just tell the truth, and they think it's hell. ║>>>  length: 78
Output: <<<║I never give 'em hell, I just tell the truth, and they think it's hell. ║>>>  length: 78
Character to be squeezed: "."
ans = ║I never give 'em hell, I just tell the truth, and they think it's hell. ║
Character to be squeezed: "."
Input:  <<<║                                                    --- Harry S Truman  ║>>>  length: 78
Output: <<<║                                                    --- Harry S Truman  ║>>>  length: 78
Character to be squeezed: "."
ans = ║                                                    --- Harry S Truman  ║
Character to be squeezed: "-"
Input:  <<<║                                                    --- Harry S Truman  ║>>>  length: 78
Output: <<<║                                                    - Harry S Truman  ║>>>  length: 76
Character to be squeezed: "-"
ans = ║                                                    - Harry S Truman  ║
Character to be squeezed: "r"
Input:  <<<║                                                    --- Harry S Truman  ║>>>  length: 78
Output: <<<║                                                    --- Hary S Truman  ║>>>  length: 77
Character to be squeezed: "r"
ans = ║                                                    --- Hary S Truman  ║

Nim

<lang Nim>import unicode, strformat

proc squeeze(s: string; ch: Rune) = 

 echo fmt"Specified character: '{ch}'"
 let original = s.toRunes
 echo fmt"Original: length = {original.len}, string = «««{s}»»»"
 var previous = Rune(0)
 var squeezed: seq[Rune]
 for rune in original:
   if rune != previous:
     squeezed.add(rune)
     previous = rune
   elif rune != ch:
     squeezed.add(rune)
 echo fmt"Squeezed: length = {squeezed.len}, string = «««{squeezed}»»»"
 echo ""


const Strings = ["", 

       "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ",
       "..1111111111111111111111111111111111111111111111111111111111111117777888",
       "I never give 'em hell, I just tell the truth, and they think it's hell. ",
       "                                                   ---  Harry S Truman  ",
       "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
       "headmistressship",
       "aardvark",
       "😍😀🙌💃😍😍😍🙌",]

const Chars = [@[Rune(' ')], @[Rune('-')], @[Rune('7')], @[Rune('.')], 

              @[Rune(' '), Rune('-'), Rune('r')],
              @[Rune('e')], @[Rune('s')], @[Rune('a')], "😍".toRunes]


for i, s in Strings: 

 for ch in Chars[i]:
   s.squeeze(ch)</lang>
Output:
Specified character: ' '
Original: length = 0, string = «««»»»
Squeezed: length = 0, string = «««»»»

Specified character: '-'
Original: length = 72, string = «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
Squeezed: length = 70, string = «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»

Specified character: '7'
Original: length = 72, string = «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
Squeezed: length = 69, string = «««..1111111111111111111111111111111111111111111111111111111111111117888»»»

Specified character: '.'
Original: length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
Squeezed: length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»

Specified character: ' '
Original: length = 72, string = «««                                                   ---  Harry S Truman  »»»
Squeezed: length = 20, string = ««« --- Harry S Truman »»»

Specified character: '-'
Original: length = 72, string = «««                                                   ---  Harry S Truman  »»»
Squeezed: length = 70, string = «««                                                   -  Harry S Truman  »»»

Specified character: 'r'
Original: length = 72, string = «««                                                   ---  Harry S Truman  »»»
Squeezed: length = 71, string = «««                                                   ---  Hary S Truman  »»»

Specified character: 'e'
Original: length = 80, string = «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
Squeezed: length = 79, string = «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»

Specified character: 's'
Original: length = 16, string = «««headmistressship»»»
Squeezed: length = 14, string = «««headmistreship»»»

Specified character: 'a'
Original: length = 8, string = «««aardvark»»»
Squeezed: length = 7, string = «««ardvark»»»

Specified character: '😍'
Original: length = 8, string = «««😍😀🙌💃😍😍😍🙌»»»
Squeezed: length = 6, string = «««😍😀🙌💃😍🙌»»»

Perl

<lang perl>use strict; use warnings; use Unicode::UCD 'charinfo';

for ( 

 [, ' '],
 ['"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ', '-'],
 ['..1111111111111111111111111111111111111111111111111111111111111117777888', '7'],
 ["I never give 'em hell, I just tell the truth, and they think it's hell. ", '.'],
 ['                                                    --- Harry S Truman  ', ' '],
 ['                                                    --- Harry S Truman  ', '-'],
 ['                                                    --- Harry S Truman  ', 'r']

) { 

   my($phrase,$char) = @$_;
   (my $squeeze = $phrase) =~ s/([$char])\1+/$1/g;
   printf "\nOriginal length: %d <<<%s>>>\nSqueezable on \"%s\": %s\nSqueezed length: %d <<<%s>>>\n",
       length($phrase), $phrase,
       charinfo(ord $char)->{'name'},
       $phrase ne $squeeze ? 'True' : 'False',
       length($squeeze), $squeeze

}</lang>

Output:
Original length: 0 <<<>>>
Squeezable on "SPACE": False
Squeezed length: 0 <<<>>>

Original length: 72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
Squeezable on "HYPHEN-MINUS": True
Squeezed length: 70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

Original length: 72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
Squeezable on "DIGIT SEVEN": True
Squeezed length: 69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

Original length: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
Squeezable on "FULL STOP": False
Squeezed length: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "SPACE": True
Squeezed length: 20 <<< --- Harry S Truman >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "HYPHEN-MINUS": True
Squeezed length: 70 <<<                                                    - Harry S Truman  >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "LATIN SMALL LETTER R": True
Squeezed length: 71 <<<                                                    --- Hary S Truman  >>>

Phix

<lang Phix>constant tests = {"", " ", 

                 `"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln `,"-",
                 "..1111111111111111111111111111111111111111111111111111111111111117777888","7",
                 "I never give 'em hell, I just tell the truth, and they think it's hell. ",".",
                 "                                                    --- Harry S Truman  "," -r"},
        fmt = """

length %2d input: <<<%s>>> length %2d squeeze(%c): <<<%s>>> """ function squeeze(sequence s, integer ch) 

   if length(s)>1 then
       integer outdx = 1
       object prev = s[1]
       for i=2 to length(s) do
           if s[i]!=prev or prev!=ch then
               prev = s[i]
               outdx += 1
               s[outdx] = prev
           end if
       end for
       s = s[1..outdx]
   end if
   return s

end function

for i=1 to length(tests) by 2 do 

   string ti = tests[i], chars = tests[i+1]
   for j=1 to length(chars) do
       string si = squeeze(ti,chars[j])
       printf(1,fmt,{length(ti),ti,length(si),chars[j],si})
   end for

end for</lang>

Output:
length  0      input: <<<>>>
length  0 squeeze( ): <<<>>>

length 72      input: <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
length 70 squeeze(-): <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

length 72      input: <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
length 69 squeeze(7): <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

length 72      input: <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
length 72 squeeze(.): <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

length 72      input: <<<                                                    --- Harry S Truman  >>>
length 20 squeeze( ): <<< --- Harry S Truman >>>

length 72      input: <<<                                                    --- Harry S Truman  >>>
length 70 squeeze(-): <<<                                                    - Harry S Truman  >>>

length 72      input: <<<                                                    --- Harry S Truman  >>>
length 71 squeeze(r): <<<                                                    --- Hary S Truman  >>>

PHP

<lang PHP><?php

function squeezeString($string, $squeezeChar) { 

   $previousChar = null;
   $squeeze = ;
   $charArray = preg_split('//u', $string, -1, PREG_SPLIT_NO_EMPTY);
   for ($i = 0 ; $i < count($charArray) ; $i++) {
       $currentChar = $charArray[$i];
       if ($previousChar !== $currentChar || $currentChar !== $squeezeChar) {
           $squeeze .= $charArray[$i];
       }
       $previousChar = $currentChar;
   }
   return $squeeze;

}

function isSqueezable($string, $squeezeChar) { 

   return ($string !== squeezeString($string, $squeezeChar));

}

$strings = array( 

   ['-', '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln '],
   ['1', '..1111111111111111111111111111111111111111111111111111111111111117777888'],
   ['l', "I never give 'em hell, I just tell the truth, and they think it's hell. "],
   [' ', '                                                    --- Harry S Truman  '],
   ['9', '0112223333444445555556666666777777778888888889999999999'],
   ['e', "The better the 4-wheel drive, the further you'll be from help when ya get stuck!"],
   ['k', "The better the 4-wheel drive, the further you'll be from help when ya get stuck!"],

); foreach ($strings as $params) { 

   list($char, $original) = $params;
   echo 'Original   : <<<', $original, '>>> (len=', mb_strlen($original), ')', PHP_EOL;
   if (isSqueezable($original, $char)) {
       $squeeze = squeezeString($original, $char);
       echo 'Squeeze(', $char, ') : <<<', $squeeze, '>>> (len=', mb_strlen($squeeze), ')', PHP_EOL, PHP_EOL;
   } else {
       echo 'Squeeze(', $char, ') : string is not squeezable (char=', $char, ')...', PHP_EOL, PHP_EOL;
   }

}</lang>

Output:
Original   : <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>> (len=72)
Squeeze(-) : <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>> (len=70)

Original   : <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>> (len=72)
Squeeze(1) : <<<..17777888>>> (len=10)

Original   : <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>> (len=72)
Squeeze(l) : <<<I never give 'em hel, I just tel the truth, and they think it's hel. >>> (len=69)

Original   : <<<                                                    --- Harry S Truman  >>> (len=72)
Squeeze( ) : <<< --- Harry S Truman >>> (len=20)

Original   : <<<0112223333444445555556666666777777778888888889999999999>>> (len=55)
Squeeze(9) : <<<0112223333444445555556666666777777778888888889>>> (len=46)

Original   : <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>> (len=80)
Squeeze(e) : <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>> (len=79)

Original   : <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>> (len=80)
Squeeze(k) : string is not squeezable (char=k)...

Prolog

<lang Prolog>squeeze_( [], _, [] ). squeeze_( [A], _, [A] ). squeeze_( [A,A|T], A, R ) :- squeeze_( [A|T], A, R ). squeeze_( [A,A|T], B, [A|R] ) :- dif( A, B ), squeeze_( [A|T], B, R ). squeeze_( [A,B|T], S, [A|R] ) :- dif( A, B ), squeeze_( [B|T], S, R ).

squeeze( Str, SqueezeChar, Collapsed ) :- 

   string_chars( Str, Chars ),
   squeeze_( Chars, SqueezeChar, Result ),
   string_chars( Collapsed, Result ).</lang>
Output:
?- squeeze( "", ' ', New ).
New = "".

?- squeeze( "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", -, New ).
New = "\"If I were two-faced, would I be wearing this one?\" - Abraham Lincoln " .

?- squeeze( "..1111111111111111111111111111111111111111111111111111111111111117777888", '7', New ).
New = "..1111111111111111111111111111111111111111111111111111111111111117888" .

?- squeeze( "I never give 'em hell, I just tell the truth, and they think it's hell. ", '.', New ).
New = "I never give 'em hell, I just tell the truth, and they think it's hell. " .

?- squeeze( "                                                    --- Harry S Truman  ", ' ', New ).
New = " --- Harry S Truman " .

?- squeeze( "                                                    --- Harry S Truman  ", '-', New ).
New = "                                                    - Harry S Truman  " .

?- squeeze( "                                                    --- Harry S Truman  ", 'r', New ).
New = "                                                    --- Hary S Truman  " .

To determine if a string is squeezed or not then the input and output strings should be the same, eg: 

?- S = "..1111111111111111111111111111111111111111111111111111111111111117888", squeeze( S, '1', S ).
false.

?- S = "..1111111111111111111111111111111111111111111111111111111111111117888", squeeze( S, '7', S ).
S = "..1111111111111111111111111111111111111111111111111111111111111117888"

Python

<lang python>from itertools import groupby

def squeezer(s, txt): 

   return .join(item if item == s else .join(grp)
                  for item, grp in groupby(txt))

if __name__ == '__main__': 

   strings = [
           "",
           '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ',
           "..1111111111111111111111111111111111111111111111111111111111111117777888",
           "I never give 'em hell, I just tell the truth, and they think it's hell. ",
           "                                                   ---  Harry S Truman  ",
           "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
           "headmistressship",
           "aardvark",
           "😍😀🙌💃😍😍😍🙌",
           ]
   squeezers = ' ,-,7,., -r,e,s,a,😍'.split(',')
   for txt, chars in zip(strings, squeezers):
       this = "Original"
       print(f"\n{this:14} Size: {len(txt)} «««{txt}»»»" )
       for ch in chars:
           this = f"Squeezer '{ch}'"
           sqz = squeezer(ch, txt)
           print(f"{this:>14} Size: {len(sqz)} «««{sqz}»»»" )</lang>
Output:
Original       Size: 0 «««»»»
  Squeezer ' ' Size: 0 «««»»»

Original       Size: 72 «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
  Squeezer '-' Size: 70 «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»

Original       Size: 72 «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
  Squeezer '7' Size: 69 «««..1111111111111111111111111111111111111111111111111111111111111117888»»»

Original       Size: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
  Squeezer '.' Size: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»

Original       Size: 72 «««                                                   ---  Harry S Truman  »»»
  Squeezer ' ' Size: 20 ««« --- Harry S Truman »»»
  Squeezer '-' Size: 70 «««                                                   -  Harry S Truman  »»»
  Squeezer 'r' Size: 71 «««                                                   ---  Hary S Truman  »»»

Original       Size: 80 «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
  Squeezer 'e' Size: 79 «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»

Original       Size: 16 «««headmistressship»»»
  Squeezer 's' Size: 14 «««headmistreship»»»

Original       Size: 8 «««aardvark»»»
  Squeezer 'a' Size: 7 «««ardvark»»»

Original       Size: 8 «««😍😀🙌💃😍😍😍🙌»»»
  Squeezer '😍' Size: 6 «««😍😀🙌💃😍🙌»»»

Raku

(formerly Perl 6)

Works with: Rakudo version 2019.07.1

<lang perl6>map { 

   my $squeeze = $^phrase;
   sink $^reg;
   $squeeze ~~ s:g/($reg)$0+/$0/;
   printf "\nOriginal length: %d <<<%s>>>\nSqueezable on \"%s\": %s\nSqueezed length: %d <<<%s>>>\n",
     $phrase.chars, $phrase, $reg.uniname, $phrase ne $squeeze, $squeeze.chars, $squeeze

}, 

 , ' ', 
 '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ', '-',
 '..1111111111111111111111111111111111111111111111111111111111111117777888', '7',
 "I never give 'em hell, I just tell the truth, and they think it's hell. ", '.',
 '                                                    --- Harry S Truman  ', ' ',
 '                                                    --- Harry S Truman  ', '-',
 '                                                    --- Harry S Truman  ', 'r'</lang>
Output:
Original length: 0 <<<>>>
Squeezable on "SPACE": False
Squeezed length: 0 <<<>>>

Original length: 72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
Squeezable on "HYPHEN-MINUS": True
Squeezed length: 70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

Original length: 72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
Squeezable on "DIGIT SEVEN": True
Squeezed length: 69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

Original length: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
Squeezable on "FULL STOP": False
Squeezed length: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "SPACE": True
Squeezed length: 20 <<< --- Harry S Truman >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "HYPHEN-MINUS": True
Squeezed length: 70 <<<                                                    - Harry S Truman  >>>

Original length: 72 <<<                                                    --- Harry S Truman  >>>
Squeezable on "LATIN SMALL LETTER R": True
Squeezed length: 71 <<<                                                    --- Hary S Truman  >>>

REXX

<lang rexx>/*REXX program "squeezes" all immediately repeated characters in a string (or strings). */ @.= /*define a default for the @. array. */

  1. .1= ' '; @.1=
  2. .2= '-'; @.2= '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln '
  3. .3= '7'; @.3= ..1111111111111111111111111111111111111111111111111111111111111117777888
  4. .4= . ; @.4= "I never give 'em hell, I just tell the truth, and they think it's hell. "
  5. .5= ' '; @.5= ' --- Harry S Truman '
  6. .6= '-'; @.6= @.5
  7. .7= 'r'; @.7= @.5
    do j=1;    L= length(@.j)                   /*obtain the length of an array element*/
    say copies('═', 105)                        /*show a separator line between outputs*/
    if j>1  &  L==0     then leave              /*if arg is null and  J>1, then leave. */
    say '    specified immediate repeatable character='     #.j      "   ('"c2x(#.j)"'x)"
    say '    length='right(L, 3)     "   input=«««" || @.j || '»»»'
    new= squeeze(@.j, #.j)
      w= length(new)
    say '    length='right(w, 3)     "  output=«««" || new || '»»»'
    end   /*j*/

exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ squeeze: procedure; parse arg y 1 $ 2,z /*get string; get immed. repeated char.*/ 

        if pos(z || z, y)==0  then return y     /*No repeated immediate char?  Return Y*/
                                                /* [↑]  Not really needed;  a speed─up.*/
                    do k=2  to length(y)        /*traipse through almost all the chars.*/
                    _= substr(y, k, 1)                      /*pick a character from  Y */
                    if _==right($, 1) & _==z then iterate   /*Same character?  Skip it.*/
                    $= $ || _                               /*append char., it's diff. */
                    end     /*j*/
        return $</lang>
output   when using the internal default inputs:
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character=      ('20'x)
    length=  0    input=«««»»»
    length=  0   output=«««»»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character= -    ('2D'x)
    length= 72    input=«««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
    length= 70   output=«««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character= 7    ('37'x)
    length= 72    input=«««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
    length= 69   output=«««..1111111111111111111111111111111111111111111111111111111111111117888»»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character= .    ('2E'x)
    length= 72    input=«««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
    length= 72   output=«««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character=      ('20'x)
    length= 72    input=«««                                                   ---  Harry S Truman  »»»
    length= 20   output=««« --- Harry S Truman »»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character= -    ('2D'x)
    length= 72    input=«««                                                   ---  Harry S Truman  »»»
    length= 70   output=«««                                                   -  Harry S Truman  »»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════
    specified immediate repeatable character= r    ('72'x)
    length= 72    input=«««                                                   ---  Harry S Truman  »»»
    length= 71   output=«««                                                   ---  Hary S Truman  »»»
═════════════════════════════════════════════════════════════════════════════════════════════════════════

Ruby

<lang ruby>strings = ["", 

       '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ',
       "..1111111111111111111111111111111111111111111111111111111111111117777888",
       "I never give 'em hell, I just tell the truth, and they think it's hell. ",
       "                                                   ---  Harry S Truman  ",
       "😍😀🙌💃😍😍😍🙌",]

squeeze_these = ["", "-", "7", ".", " -r", "😍"]

strings.zip(squeeze_these).each do |str, st| 

 puts "original:     «««#{str}»»» (size #{str.size})"
 st.chars.each do |c|
   ssq = str.squeeze(c)
   puts "#{c.inspect}-squeezed: «««#{ssq}»»» (size #{ssq.size})" 
 end
 puts

end </lang>

Output:
original:     «««»»» (size 0)

original:     «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»» (size 72)
"-"-squeezed: «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»» (size 70)

original:     «««..1111111111111111111111111111111111111111111111111111111111111117777888»»» (size 72)
"7"-squeezed: «««..1111111111111111111111111111111111111111111111111111111111111117888»»» (size 69)

original:     «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (size 72)
"."-squeezed: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (size 72)

original:     «««                                                   ---  Harry S Truman  »»» (size 72)
" "-squeezed: ««« --- Harry S Truman »»» (size 20)
"-"-squeezed: «««                                                   -  Harry S Truman  »»» (size 70)
"r"-squeezed: «««                                                   ---  Hary S Truman  »»» (size 71)

original:     «««😍😀🙌💃😍😍😍🙌»»» (size 8)
"😍"-squeezed: «««😍😀🙌💃😍🙌»»» (size 6)

Rust

See collapsible strings for the alternative implementation approach.

<lang Rust>fn squeezable_string<'a>(s: &'a str, squeezable: char) -> impl Iterator<Item = char> + 'a { 

   let mut previous = None;

   s.chars().filter(move |c| match previous {
       Some(p) if p == squeezable && p == *c => false,
       _ => {
           previous = Some(*c);
           true
       }
   })

}

fn main() { 

   fn show(input: &str, c: char) {
       println!("Squeeze: '{}'", c);
       println!("Input ({} chars): \t{}", input.chars().count(), input);
       let output: String = squeezable_string(input, c).collect();
       println!("Output ({} chars): \t{}", output.chars().count(), output);
       println!();
   }

   let harry = r#"I never give 'em hell, I just tell the truth, and they think it's hell.
   ---  Harry S Truman"#;

   #[rustfmt::skip]
   let inputs = [
       ("", ' '),
       (r#""If I were two-faced, would I be wearing this one?" --- Abraham Lincoln "#, '-'),
       ("..1111111111111111111111111111111111111111111111111111111111111117777888", '7'),
       (harry, ' '),
       (harry, '-'),
       (harry, 'r'),
       ("The better the 4-wheel drive, the further you'll be from help when ya get stuck!", 'e'),
       ("headmistressship", 's'),
   ];

   inputs.iter().for_each(|(input, c)| show(input, *c));

}</lang>

Sidef

<lang ruby>func squeeze(str, c) { 

   str.gsub(Regex("(" + c.escape + ")" + '\1+'), {|s1| s1 })

}

var strings = ["", 

       '"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln ',
       "..1111111111111111111111111111111111111111111111111111111111111117777888",
       "I never give 'em hell, I just tell the truth, and they think it's hell. ",
       "                                                   ---  Harry S Truman  ",
       "😍😀🙌💃😍😍😍🙌"]

var squeeze_these = ["", "-", "7", ".", " -r", "😍"]

[strings, squeeze_these].zip {|str,st| 

   say "    original: «««#{str}»»» (length: #{str.len})"
   st.each {|c|
       var ssq = squeeze(str, c)
       say "'#{c}'-squeezed: «««#{ssq}»»» (length: #{ssq.len})"
   }
   say

}</lang>

Output:
    original: «««»»» (length: 0)

    original: «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»» (length: 72)
'-'-squeezed: «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»» (length: 70)

    original: «««..1111111111111111111111111111111111111111111111111111111111111117777888»»» (length: 72)
'7'-squeezed: «««..1111111111111111111111111111111111111111111111111111111111111117888»»» (length: 69)

    original: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length: 72)
'.'-squeezed: «««I never give 'em hell, I just tell the truth, and they think it's hell. »»» (length: 72)

    original: «««                                                   ---  Harry S Truman  »»» (length: 72)
' '-squeezed: ««« --- Harry S Truman »»» (length: 20)
'-'-squeezed: «««                                                   -  Harry S Truman  »»» (length: 70)
'r'-squeezed: «««                                                   ---  Hary S Truman  »»» (length: 71)

    original: «««😍😀🙌💃😍😍😍🙌»»» (length: 8)
'😍'-squeezed: «««😍😀🙌💃😍🙌»»» (length: 6)

Tcl

<lang tcl># Set test data as a list pairing even and odd values

  1. as test string and squeeze character(s) respectively.

set test { 

   {} {" "}
   {"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln } {"-"}
   {..1111111111111111111111111111111111111111111111111111111111111117777888} {"7"}
   {I never give 'em hell, I just tell the truth, and they think it's hell. } {"."} ;# '
   {                                                    --- Harry S Truman  } {" " "-" "r"}
   {The better the 4-wheel drive, the further you'll be from help when ya get stuck!} {"e"} ;# '
   {headmistressship} {"s"}

}

foreach {str chrs} $test { 

   foreach c $chrs {
       # Escape non-word replacement characters (such as .)
       set c [regsub -all {\W} $c {\\&}]

       # Uses regexp lookbehind to detect repeated characters
       set re [subst -noback {($c)(\1+)}] ;# build expression
       set sub [regsub -all $re $str {\1}]

       # Output
       puts [format "Original (length %3d): %s" [string length $str] $str]
       puts [format "Subbed   (length %3d): %s" [string length $sub] $sub]
       puts ----------------------
   }

}

</lang>

Output:
Original (length   0):
Subbed   (length   0):
----------------------
Original (length  72): "If I were two-faced, would I be wearing this one?" --- Abraham Lincoln
Subbed   (length  70): "If I were two-faced, would I be wearing this one?" - Abraham Lincoln
----------------------
Original (length  72): ..1111111111111111111111111111111111111111111111111111111111111117777888
Subbed   (length  69): ..1111111111111111111111111111111111111111111111111111111111111117888
----------------------
Original (length  72): I never give 'em hell, I just tell the truth, and they think it's hell.
Subbed   (length  72): I never give 'em hell, I just tell the truth, and they think it's hell.
----------------------
Original (length  72):                                                     --- Harry S Truman
Subbed   (length  20):  --- Harry S Truman
----------------------
Original (length  72):                                                     --- Harry S Truman
Subbed   (length  70):                                                     - Harry S Truman
----------------------
Original (length  72):                                                     --- Harry S Truman
Subbed   (length  71):                                                     --- Hary S Truman
----------------------
Original (length  80): The better the 4-wheel drive, the further you'll be from help when ya get stuck!
Subbed   (length  79): The better the 4-whel drive, the further you'll be from help when ya get stuck!
----------------------
Original (length  16): headmistressship
Subbed   (length  14): headmistreship
----------------------

Visual Basic .NET

Translation of: C#

<lang vbnet>Imports System.Linq.Enumerable

Module Module1 

   Function Squeeze(s As String, c As Char) As String
       If String.IsNullOrEmpty(s) Then
           Return ""
       End If
       Return s(0) + New String(Range(1, s.Length - 1).Where(Function(i) s(i) <> c OrElse s(i) <> s(i - 1)).Select(Function(i) s(i)).ToArray())
   End Function

   Sub SqueezeAndPrint(s As String, c As Char)
       Console.WriteLine("squeeze: '{0}'", c)
       Console.WriteLine("old: {0} «««{1}»»»", s.Length, s)
       s = Squeeze(s, c)
       Console.WriteLine("new: {0} «««{1}»»»", s.Length, s)
   End Sub

   Sub Main()
       Const QUOTE = """"

       SqueezeAndPrint("", " ")
       SqueezeAndPrint(QUOTE & "If I were two-faced, would I be wearing this one?" & QUOTE & " --- Abraham Lincoln ", "-")
       SqueezeAndPrint("..1111111111111111111111111111111111111111111111111111111111111117777888", "7")
       SqueezeAndPrint("I never give 'em hell, I just tell the truth, and they think it's hell. ", ".")

       Dim s = "                                                    --- Harry S Truman  "
       SqueezeAndPrint(s, " ")
       SqueezeAndPrint(s, "-")
       SqueezeAndPrint(s, "r")
   End Sub

End Module</lang>

Output:
squeeze: ' '
old: 0 «««»»»
new: 0 «««»»»
squeeze: '-'
old: 72 «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
new: 70 «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»
squeeze: '7'
old: 72 «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
new: 69 «««..1111111111111111111111111111111111111111111111111111111111111117888»»»
squeeze: '.'
old: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
new: 72 «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
squeeze: ' '
old: 72 «««                                                    --- Harry S Truman  »»»
new: 20 ««« --- Harry S Truman »»»
squeeze: '-'
old: 72 «««                                                    --- Harry S Truman  »»»
new: 70 «««                                                    - Harry S Truman  »»»
squeeze: 'r'
old: 72 «««                                                    --- Harry S Truman  »»»
new: 71 «««                                                    --- Hary S Truman  »»»

Wren

Translation of: Go
Library: Wren-fmt

<lang ecmascript>import "/fmt" for Fmt

// Returns squeezed string, original and new lengths in // unicode code points (not normalized). var squeeze = Fn.new { |s, ch| 

   var c = s.codePoints.toList
   var le = c.count
   if (le < 2) return [s, le, le]
   for (i in le-2..0) {
       if (c[i] == ch.codePoints[0] && c[i] == c[i+1]) c.removeAt(i)
   }
   var cc = c.reduce("") { |acc, cp| acc + String.fromCodePoint(cp) }
   return [cc, le, cc.count]

}

var strings = [ 

   "",
   "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ",
   "..1111111111111111111111111111111111111111111111111111111111111117777888",
   "I never give 'em hell, I just tell the truth, and they think it's hell. ",
   "                                                   ---  Harry S Truman  ",
   "The better the 4-wheel drive, the further you'll be from help when ya get stuck!",
   "headmistressship",
   "aardvark",
   "😍😀🙌💃😍😍😍🙌"

]

var chars = [ [" "], ["-"], ["7"], ["."], [" ", "-", "r"], ["e"], ["s"], ["a"], ["😍"] ]

var i = 0 for (s in strings) { 

   for (ch in chars[i]) {
       var r = squeeze.call(s, ch)
       System.print("Specified character = '%(ch)'")
       System.print("original : length = %(Fmt.d(2, r[1])), string = «««%(s)»»»")
       System.print("squeezed : length = %(Fmt.d(2, r[2])), string = «««%(r[0])»»»\n")
   }
   i = i + 1

}</lang>

Output:
Specified character = ' '
original : length =  0, string = «««»»»
squeezed : length =  0, string = «««»»»

Specified character = '-'
original : length = 72, string = «««"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln »»»
squeezed : length = 70, string = «««"If I were two-faced, would I be wearing this one?" - Abraham Lincoln »»»

Specified character = '7'
original : length = 72, string = «««..1111111111111111111111111111111111111111111111111111111111111117777888»»»
squeezed : length = 69, string = «««..1111111111111111111111111111111111111111111111111111111111111117888»»»

Specified character = '.'
original : length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»
squeezed : length = 72, string = «««I never give 'em hell, I just tell the truth, and they think it's hell. »»»

Specified character = ' '
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 20, string = ««« --- Harry S Truman »»»

Specified character = '-'
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 70, string = «««                                                   -  Harry S Truman  »»»

Specified character = 'r'
original : length = 72, string = «««                                                   ---  Harry S Truman  »»»
squeezed : length = 71, string = «««                                                   ---  Hary S Truman  »»»

Specified character = 'e'
original : length = 80, string = «««The better the 4-wheel drive, the further you'll be from help when ya get stuck!»»»
squeezed : length = 79, string = «««The better the 4-whel drive, the further you'll be from help when ya get stuck!»»»

Specified character = 's'
original : length = 16, string = «««headmistressship»»»
squeezed : length = 14, string = «««headmistreship»»»

Specified character = 'a'
original : length =  8, string = «««aardvark»»»
squeezed : length =  7, string = «««ardvark»»»

Specified character = '😍'
original : length =  8, string = «««😍😀🙌💃😍😍😍🙌»»»
squeezed : length =  6, string = «««😍😀🙌💃😍🙌»»»

zkl

<lang zkl>fcn squeeze(c,str){ // Works with UTF-8 

  s,cc,sz,n := Data(Void,str), String(c,c), c.len(), 0; // byte buffer in case of LOTs of deletes
  while(Void != (n=s.find(cc,n))){ str=s.del(n,sz) }  // and searching is faster for big strings
  s.text

}</lang> <lang zkl>strings:=T( T("",""), T("-","\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "), T("7","..1111111111111111111111111111111111111111111111111111111111111117777888"), T(" ","I never give 'em hell, I just tell the truth, and they think it's hell. "), T(" "," --- Harry S Truman "), T("-"," --- Harry S Truman "), T("r"," --- Harry S Truman "), T("e","The better the 4-wheel drive, the further you'll be from help when ya get stuck!"), T("s","headmistressship"), T("\Ubd;","\Ubc;\Ubd;\Ubd;\Ube;"), );

foreach c,s in (strings){ 

  println("Squeeze: \"",c,"\"");
  println("Before: %2d <<<%s>>>".fmt(s.len(-8),s));
  sstr:=squeeze(c,s);
  println("After:  %2d <<<%s>>>\n".fmt(sstr.len(-8),sstr));

}</lang>

Output:
Squeeze: ""
Before:  0 <<<>>>
After:   0 <<<>>>

Squeeze: "-"
Before: 72 <<<"If I were two-faced, would I be wearing this one?" --- Abraham Lincoln >>>
After:  70 <<<"If I were two-faced, would I be wearing this one?" - Abraham Lincoln >>>

Squeeze: "7"
Before: 72 <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>
After:  69 <<<..1111111111111111111111111111111111111111111111111111111111111117888>>>

Squeeze: " "
Before: 72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>
After:  72 <<<I never give 'em hell, I just tell the truth, and they think it's hell. >>>

Squeeze: " "
Before: 72 <<<                                                    --- Harry S Truman  >>>
After:  20 <<< --- Harry S Truman >>>

Squeeze: "-"
Before: 72 <<<                                                    --- Harry S Truman  >>>
After:  70 <<<                                                    - Harry S Truman  >>>

Squeeze: "r"
Before: 72 <<<                                                   ---  Harry S Truman  >>>
After:  71 <<<                                                   ---  Hary S Truman  >>>

Squeeze: "e"
Before: 80 <<<The better the 4-wheel drive, the further you'll be from help when ya get stuck!>>>
After:  79 <<<The better the 4-whel drive, the further you'll be from help when ya get stuck!>>>

Squeeze: "s"
Before: 16 <<<headmistressship>>>
After:  14 <<<headmistreship>>>

Squeeze: "½"
Before:  4 <<<¼½½¾>>>
After:   3 <<<¼½¾>>>
Retrieved from "https://rosettacode.org/wiki/Determine_if_a_string_is_squeezable?oldid=296151"