Strip whitespace from a string/Top and tail
Demonstrate how to strip leading and trailing whitespace from a string.
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
The solution should demonstrate how to achieve the following three results:
- String with leading whitespace removed
- String with trailing whitespace removed
- String with both leading and trailing whitespace removed
For the purposes of this task whitespace includes non printable characters such as the space character, the tab character, and other such characters that have no corresponding graphical representation.
- Metrics
- Counting
- Word frequency
- Letter frequency
- Jewels and stones
- I before E except after C
- Bioinformatics/base count
- Count occurrences of a substring
- Count how many vowels and consonants occur in a string
- Remove/replace
- XXXX redacted
- Conjugate a Latin verb
- Remove vowels from a string
- String interpolation (included)
- Strip block comments
- Strip comments from a string
- Strip a set of characters from a string
- Strip whitespace from a string -- top and tail
- Strip control codes and extended characters from a string
- Anagrams/Derangements/shuffling
- Word wheel
- ABC problem
- Sattolo cycle
- Knuth shuffle
- Ordered words
- Superpermutation minimisation
- Textonyms (using a phone text pad)
- Anagrams
- Anagrams/Deranged anagrams
- Permutations/Derangements
- Find/Search/Determine
- ABC words
- Odd words
- Word ladder
- Semordnilap
- Word search
- Wordiff (game)
- String matching
- Tea cup rim text
- Alternade words
- Changeable words
- State name puzzle
- String comparison
- Unique characters
- Unique characters in each string
- Extract file extension
- Levenshtein distance
- Palindrome detection
- Common list elements
- Longest common suffix
- Longest common prefix
- Compare a list of strings
- Longest common substring
- Find common directory path
- Words from neighbour ones
- Change e letters to i in words
- Non-continuous subsequences
- Longest common subsequence
- Longest palindromic substrings
- Longest increasing subsequence
- Words containing "the" substring
- Sum of the digits of n is substring of n
- Determine if a string is numeric
- Determine if a string is collapsible
- Determine if a string is squeezable
- Determine if a string has all unique characters
- Determine if a string has all the same characters
- Longest substrings without repeating characters
- Find words which contains all the vowels
- Find words which contains most consonants
- Find words which contains more than 3 vowels
- Find words which first and last three letters are equals
- Find words which odd letters are consonants and even letters are vowels or vice_versa
- Formatting
- Substring
- Rep-string
- Word wrap
- String case
- Align columns
- Literals/String
- Repeat a string
- Brace expansion
- Brace expansion using ranges
- Reverse a string
- Phrase reversals
- Comma quibbling
- Special characters
- String concatenation
- Substring/Top and tail
- Commatizing numbers
- Reverse words in a string
- Suffixation of decimal numbers
- Long literals, with continuations
- Numerical and alphabetical suffixes
- Abbreviations, easy
- Abbreviations, simple
- Abbreviations, automatic
- Song lyrics/poems/Mad Libs/phrases
- Mad Libs
- Magic 8-ball
- 99 Bottles of Beer
- The Name Game (a song)
- The Old lady swallowed a fly
- The Twelve Days of Christmas
- Tokenize
- Text between
- Tokenize a string
- Word break problem
- Tokenize a string with escaping
- Split a character string based on change of character
- Sequences
Ada
<lang Ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Strings; use Ada.Strings; with Ada.Strings.Fixed; use Ada.Strings.Fixed; procedure StripDemo is
str : String := " Jabberwocky ";
begin
Put_Line ("'" & Trim (str, Left) & "'");
Put_Line ("'" & Trim (str, Right) & "'");
Put_Line ("'" & Trim (str, Both) & "'");
end StripDemo;</lang>
- Output:
'Jabberwocky ' ' Jabberwocky' 'Jabberwocky'
ALGOL 68
version 1
<lang algol68># returns "text" with leading non-printing characters removed # PROC trim leading whitespace = ( STRING text )STRING: BEGIN
INT pos := LWB text;
WHILE
IF pos > UPB text
THEN
FALSE
ELSE
text[ pos ] <= " "
FI
DO
pos +:= 1
OD;
text[ pos : ]
END; # trim leading whitespace #
- returns "text" with trailing non-printing characters removed #
PROC trim trailing whitespace = ( STRING text )STRING: BEGIN
INT pos := UPB text;
WHILE
IF pos < LWB text
THEN
FALSE
ELSE
text[ pos ] <= " "
FI
DO
pos -:= 1
OD;
text[ : pos ]
END; # trim trailing whitespace #
- returns "text" with leading and trailing non-printing characters removed #
PROC trim whitespace = ( STRING text )STRING: BEGIN
trim trailing whitespace( trim leading whitespace( text ) )
END; # trim whitespace #
main:(
STRING test = " leading and trailing spaces surrounded this text ";
print( ( "trim leading: """ + trim leading whitespace ( test ) + """", newline ) ); print( ( "trim trailing: """ + trim trailing whitespace( test ) + """", newline ) ); print( ( "trim both: """ + trim whitespace ( test ) + """", newline ) )
)</lang>
- Output:
trim leading: "leading and trailing spaces surrounded this text " trim trailing: " leading and trailing spaces surrounded this text" trim both: "leading and trailing spaces surrounded this text"
version 2
A single procedure that trims leading space, trailing space, or both.
<lang algol68>#
string_trim Trim leading and trailing whitespace from string.
@param str A string. @return A string trimmed of leading and trailing white space.
PROC string_trim = (STRING str) STRING: (
INT i := 1, j := 0;
WHILE str[i] = blank DO
i +:= 1
OD;
WHILE str[UPB str - j] = blank DO
j +:= 1
OD;
str[i:UPB str - j]
);
test: (
IF string_trim(" foobar") /= "foobar" THEN
print(("string_trim(' foobar'): expected 'foobar'; actual: "
+ string_trim(" foobar"), newline)) FI;
IF string_trim("foobar ") /= "foobar" THEN
print(("string_trim('foobar '): expected 'foobar'; actual: "
+ string_trim("foobar "), newline)) FI;
IF string_trim(" foobar ") /= "foobar" THEN
print(("string_trim(' foobar '): expected 'foobar'; actual: "
+ string_trim(" foobar "), newline)) FI
)</lang>
AppleScript
<lang AppleScript>use framework "Foundation" -- "OS X" Yosemite onwards, for NSRegularExpression
-- STRIP WHITESPACE ----------------------------------------------------------
-- isSpace :: Char -> Bool on isSpace(c)
((length of c) = 1) and regexTest("\\s", c)
end isSpace
-- stripStart :: Text -> Text on stripStart(s)
dropWhile(isSpace, s) as text
end stripStart
-- stripEnd :: Text -> Text on stripEnd(s)
dropWhileEnd(isSpace, s) as text
end stripEnd
-- strip :: Text -> Text on strip(s)
dropAround(isSpace, s) as text
end strip
-- TEST ----------------------------------------------------------------------
on run
set strText to " \t\t \n \r Much Ado About Nothing \t \n \r "
script arrowed
on |λ|(x)
"-->" & x & "<--"
end |λ|
end script
map(arrowed, [stripStart(strText), stripEnd(strText), strip(strText)])
-- {"-->Much Ado About Nothing
--
-- <--", "-->
--
-- Much Ado About Nothing<--", "-->Much Ado About Nothing<--"}
end run
-- GENERIC FUNCTIONS ---------------------------------------------------------
-- dropAround :: (Char -> Bool) -> [a] -> [a] on dropAround(p, xs)
dropWhile(p, dropWhileEnd(p, xs))
end dropAround
-- dropWhile :: (a -> Bool) -> [a] -> [a] on dropWhile(p, xs)
tell mReturn(p)
set lng to length of xs
set i to 1
repeat while i ≤ lng and |λ|(item i of xs)
set i to i + 1
end repeat
end tell
if i ≤ lng then
items i thru lng of xs
else
{}
end if
end dropWhile
-- dropWhileEnd :: (a -> Bool) -> [a] -> [a] on dropWhileEnd(p, xs)
tell mReturn(p)
set i to length of xs
repeat while i > 0 and |λ|(item i of xs)
set i to i - 1
end repeat
end tell
if i > 0 then
items 1 thru i of xs
else
{}
end if
end dropWhileEnd
-- map :: (a -> b) -> [a] -> [b] on map(f, xs)
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- Lift 2nd class handler function into 1st class script wrapper -- mReturn :: Handler -> Script on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn
-- regexTest :: RegexPattern -> String -> Bool on regexTest(strRegex, str)
set ca to current application
set oString to ca's NSString's stringWithString:str
((ca's NSRegularExpression's regularExpressionWithPattern:strRegex ¬
options:((ca's NSRegularExpressionAnchorsMatchLines as integer)) ¬
|error|:(missing value))'s firstMatchInString:oString options:0 ¬
range:{location:0, |length|:oString's |length|()}) is not missing value
end regexTest</lang>
- Output:
<lang AppleScript>{"-->Much Ado About Nothing
<--", "--> Much Ado About Nothing<--", "-->Much Ado About Nothing<--"}</lang>
Arturo
<lang rebol>str: " Hello World "
print [pad "strip all:" 15 ">" strip str "<"] print [pad "strip leading:" 15 ">" strip.start str "<"] print [pad "strip trailing:" 15 ">" strip.end str "<"]</lang>
- Output:
strip all: > Hello World < strip leading: > Hello World < strip trailing: > Hello World <
AutoHotkey
AutoHotkey_L and v2 contain a Trim function <lang AutoHotkey>string := " abc " MsgBox % clipboard := "<" LTrim(string) ">`n<" RTrim(string) ">`n<" . Trim(string) ">"</lang>
- Output:
<abc > < abc> <abc>
AWK
- [:graph:] is a POSIX character class for characters that are both printable and visible. The following strips the entire non-[:graph:] character set. A simplified version for the more common task of removing only spaces and tabs follows it.
<lang awk>function trimleft(str ,c, out, arr) {
c = split(str, arr, "") for ( i = match(str, /graph:/); i <= c; i++) out = out arr[i] return out
}
function reverse(str ,n, tmp, j, out) {
n = split(str, tmp, "")
for (j = n; j > 0; j--)
out = out tmp[j]
return out
}
function trimright(str) {
return reverse(trimleft(reverse(str)))
}
function trim(str) {
return trimright(trimleft(str))
}
BEGIN {
str = " \x0B\t\r\n \xA0 Hellö \xA0\x0B\t\r\n " print "string = |" str "|" print "left = |" trimleft(str) "|" print "right = |" trimright(str) "|" print "both = |" trim(str) "|"
}</lang>
- Output from 26 May 2015:
string = | ▒ Hellö ▒ | left = |Hellö ▒ | right = | ▒ Hellö| both = |Hellö|
Simplified for removing [:blank:] (spaces and tabs) or [:space:] (for [ \t\r\n\v\f] ). This method does not work using [:graph:]
<lang awk>function trim(str) {
gsub(/^blank:+/,"", str) # Remove leading gsub(/blank:+$/,"", str) # Remove trailing gsub(/^blank:+|blank:+$/, "", str) # Remove both return str;
}</lang>
BaCon
<lang qbasic> '---Remove leading whitespace PRINT CHOP$(" String with spaces "," ",1)
'---Remove trailing whitespace PRINT CHOP$(" String with spaces "," ",2)
'---Remove both leading and trailing whitespace PRINT CHOP$(" String with spaces "," ",0) </lang>
BASIC
<lang qbasic> mystring$=ltrim(mystring$) ' remove leading whitespace
mystring$=rtrim(mystring$) ' remove trailing whitespace mystring$=ltrim(rtrim(mystring$)) ' remove both leading and trailing whitespace</lang>
BBC BASIC
<lang bbcbasic> REM Remove leading whitespace:
WHILE ASC(A$)<=32 A$ = MID$(A$,2) : ENDWHILE
REM Remove trailing whitespace:
WHILE ASC(RIGHT$(A$))<=32 A$ = LEFT$(A$) : ENDWHILE
REM Remove both leading and trailing whitespace:
WHILE ASC(A$)<=32 A$ = MID$(A$,2) : ENDWHILE
WHILE ASC(RIGHT$(A$))<=32 A$ = LEFT$(A$) : ENDWHILE</lang>
Bracmat
Greedy pattern matching is not Bracmat's strongest field. So instead of a pattern that globs all white space characters, we have a pattern that finds the first non-whitespace character. That character, and the remainder of the subject string, constitute a left trimmed string. To do a right trim, we reverse the string, do a left trim and reverse back. <lang bracmat>( ( ltrim
= s
. @( !arg
: ?
( ( %@
: ~( " "
| \a
| \b
| \n
| \r
| \t
| \v
)
)
?
: ?s
)
)
& !s
)
& (rtrim=.rev$(ltrim$(rev$!arg))) & (trim=.rev$(ltrim$(rev$(ltrim$!arg)))) & (string=" \a Hear the sound? \v
\r ") & out$(str$("Input:[" !string "]")) & out$(str$("ltrim:[" ltrim$!string "]")) & out$(str$("rtrim:[" rtrim$!string "]")) & out$(str$("trim :[" trim$!string "]")) & );</lang> Output (Notice the effect of the ancient \a (alarm) and \v (vertical tab)):
Input:[ Hear
the sound?
♂
]
ltrim:[Hear
the sound?
♂
]
rtrim:[ Hear
the sound?]
trim :[Hear
the sound?]
Burlesque
<lang burlesque> blsq ) " this is a string "t[ "this is a string " blsq ) " this is a string "t] " this is a string" blsq ) " this is a string "tt "this is a string" </lang>
C
<lang c>#include <stdio.h>
- include <stdlib.h>
- include <string.h>
- include <ctype.h>
char *rtrim(const char *s) {
while( isspace(*s) || !isprint(*s) ) ++s; return strdup(s);
}
char *ltrim(const char *s) {
char *r = strdup(s);
if (r != NULL)
{
char *fr = r + strlen(s) - 1;
while( (isspace(*fr) || !isprint(*fr) || *fr == 0) && fr >= r) --fr;
*++fr = 0;
}
return r;
}
char *trim(const char *s) {
char *r = rtrim(s); char *f = ltrim(r); free(r); return f;
}
const char *a = " this is a string ";
int main() {
char *b = rtrim(a); char *c = ltrim(a); char *d = trim(a);
printf("'%s'\n'%s'\n'%s'\n", b, c, d);
free(b);
free(c);
free(d);
return 0;
}</lang>
C#
<lang csharp>using System;
public class TrimExample {
public static void Main(String[] args)
{
const string toTrim = " Trim me ";
Console.WriteLine(Wrap(toTrim.TrimStart()));
Console.WriteLine(Wrap(toTrim.TrimEnd()));
Console.WriteLine(Wrap(toTrim.Trim()));
}
private static string Wrap(string s)
{
return "'" + s + "'";
}
}</lang>
- Output:
'Trim me ' ' Trim me' 'Trim me'
C++
<lang cpp>#include <boost/algorithm/string.hpp>
- include <string>
- include <iostream>
int main( ) {
std::string testphrase( " There are unwanted blanks here! " ) ; std::string lefttrimmed = boost::trim_left_copy( testphrase ) ; std::string righttrimmed = boost::trim_right_copy( testphrase ) ; std::cout << "The test phrase is :" << testphrase << "\n" ; std::cout << "Trimmed on the left side :" << lefttrimmed << "\n" ; std::cout << "Trimmed on the right side :" << righttrimmed << "\n" ; boost::trim( testphrase ) ; std::cout << "Trimmed on both sides :" << testphrase << "\n" ; return 0 ;
}</lang>
- Output:
The test phrase is : There are unwanted blanks here! Trimmed on the left side :There are unwanted blanks here! Trimmed on the right side : There are unwanted blanks here! Trimmed on both sides :There are unwanted blanks here!
Clojure
<lang clojure> (use 'clojure.string) (triml " my string ") => "my string " (trimr " my string ") => " my string" (trim " \t\r\n my string \t\r\n ") => "my string" </lang>
COBOL
<lang cobol>DISPLAY "'" FUNCTION TRIM(str, LEADING) "'" DISPLAY "'" FUNCTION TRIM(str, TRAILING) "'" DISPLAY "'" FUNCTION TRIM(str) "'"</lang>
<lang cobol>DISPLAY "'" FUNCTION TRIML(str) "'" DISPLAY "'" FUNCTION TRIMR(str) "'" DISPLAY "'" FUNCTION TRIM(str) "'"</lang>
Common Lisp
<lang lisp>; Common whitespace characters (defvar *whitespace* '(#\Space #\Newline #\Tab))
(defvar str " foo bar baz ")
(string-trim *whitespace* str)
- -> "foo bar baz"
(string-left-trim *whitespace* str)
- -> "foo bar baz "
(string-right-trim *whitespace* str)
- -> " foo bar baz"
- Whitespace characters defined by Unicode for
- implementations which support it (e.g. CLISP, SBCL).
- (see http://www.unicode.org/Public/UCD/latest/ucd/PropList.txt)
(defvar *unicode-whitespace*
'(#\u0009 #\u000a #\u000b #\u000c #\u000d #\u0020 #\u0085 #\u00a0 #\u1680 #\u2000 #\u2001 #\u2002 #\u2003 #\u2004 #\u2005 #\u2006 #\u2007 #\u2008 #\u2009 #\u200a #\u2028 #\u2029 #\u202f #\u205f #\u3000))
(defvar unicode-str
(format nil "~C~Cfoo~Cbar~Cbaz~C~C"
#\u2000 #\u2003 #\u0020 #\u00a0 #\u0009 #\u202f))
(string-trim *unicode-whitespace* unicode-str)
- -> "foo bar baz"
(string-left-trim *unicode-whitespace* unicode-str)
- -> "foo bar baz "
(string-right-trim *unicode-whitespace* unicode-str)
- -> " foo bar baz"</lang>
Crystal
<lang Ruby> def strip_whitepace(s)
puts s.lstrip() puts s.rstrip() puts s.strip()
end
strip_whitepace("\t hello \t")
- => hello
- => hello
- => hello
</lang>
D
<lang d>import std.stdio, std.string;
void main() {
auto s = " \t \r \n String with spaces \t \r \n "; assert(s.stripLeft() == "String with spaces \t \r \n "); assert(s.stripRight() == " \t \r \n String with spaces"); assert(s.strip() == "String with spaces");
}</lang>
Delphi/Pascal
<lang Delphi>program StripWhitespace;
{$APPTYPE CONSOLE}
uses SysUtils;
const
TEST_STRING = ' String with spaces ';
begin
Writeln('"' + TEST_STRING + '"');
Writeln('"' + TrimLeft(TEST_STRING) + '"');
Writeln('"' + TrimRight(TEST_STRING) + '"');
Writeln('"' + Trim(TEST_STRING) + '"');
end.</lang>
DWScript
<lang Delphi>const TEST_STRING = ' String with spaces ';
PrintLn('"' + TEST_STRING + '"'); PrintLn('"' + TrimLeft(TEST_STRING) + '"'); PrintLn('"' + TrimRight(TEST_STRING) + '"'); PrintLn('"' + Trim(TEST_STRING) + '"');</lang>
EchoLisp
<lang scheme> (define witt
" The limits of my world are the limits of my langage. ")
(string->html (string-trim witt))
→ "The limits of my world are the limits of my langage."
(string->html (string-trim-left witt))
→ "The limits of my world are the limits of my langage. "
(string->html (string-trim-right witt))
→ " The limits of my world are the limits of my langage."
</lang>
Elena
ELENA 4.x : <lang elena>import extensions;
public program() {
var toTrim := " Trim me ";
console.printLine("'", toTrim.trimLeft(),"'");
console.printLine("'", toTrim.trimRight(),"'");
console.printLine("'", toTrim.trim(),"'");
}</lang>
- Output:
'Trim me ' ' Trim me' 'Trim me'
Elixir
<lang elixir>str = "\n \t foo \n\t bar \t \n" IO.inspect String.strip(str) IO.inspect String.rstrip(str) IO.inspect String.lstrip(str)</lang>
- Output:
"foo \n\t bar" "\n \t foo \n\t bar" "foo \n\t bar \t \n"
Emacs Lisp
trim left
<lang Emacs Lisp> (defun trim-l (str)
(replace-regexp-in-string "^ +" "" str) )
(setq str " left between right ") (insert (trim-l str) )
</lang> Output:
left between right
trim right
<lang Emacs Lisp> (defun trim-r (str)
(replace-regexp-in-string " +$" "" str) )
(setq str " left between right ") (insert (trim-r str) ) </lang> Output:
left between right
trim version 1
<lang Emacs Lisp> (defun trim (str)
(trim-l (trim-r str) ))
(setq str " left between right ") (insert (trim str) ) </lang> Output:
left between right
trim version 2
<lang Emacs Lisp> (defun trim (str)
(mapconcat 'identity (split-string str) " ") )
(setq str " left between right ") (insert (trim str) ) </lang> Output:
left between right
Erlang
<lang erlang>% Implemented by Arjun Sunel 1> string:strip(" Hello World! ", left). %remove leading whitespaces "Hello World! "
2> string:strip(" Hello World! ", right). % remove trailing whitespaces " Hello World!"
3> string:strip(" Hello World! ", both). % remove both leading and trailing whitespace "Hello World!" </lang>
Euphoria
A string (sequence) 'A B C' is surrounded by unwanted characters including spaces. The trim() function Trims "all items in the supplied set from both the left end (head/start) and right end (tail/end) of a sequence." It's part of the standard library, std/text.e .
Special characters in a string literal are typed 'escaped' with a '\' followed by one character. Other special characters are written using escaped hexadecimal , example : \x04 to represent hexadecimal ascii 04 or \u2A7C for 4-digit UTF, or more than two digit ascii characters : \u0127.
<lang euphoria>include std/console.e include std/text.e
sequence removables = " \t\n\r\x05\u0234\" " sequence extraSeq = " \x05\r \" A B C \n \t\t \u0234 \r\r \x05 "
extraSeq = trim(extraSeq,removables) --the work is done by the trim function
--only output programming next : printf(1, "String Trimmed is now: %s \r\n", {extraSeq} ) --print the resulting string to screen
for i = 1 to length(extraSeq) do --loop over each character in the sequence.
printf(1, "String element %d", i) --to look at more detail, printf(1, " : %d\r\n", extraSeq[i])--print integer values(ascii) of the string.
end for
any_key()</lang>
Output:
String Trimmed is now: A B C String element 1 : 65 String element 2 : 32 String element 3 : 32 String element 4 : 66 String element 5 : 32 String element 6 : 32 String element 7 : 67 Press Any Key to continue...
F#
<lang fsharp>[<EntryPoint>] let main args =
printfn "%A" (args.[0].TrimStart()) printfn "%A" (args.[0].TrimEnd()) printfn "%A" (args.[0].Trim()) 0</lang>
>rosetta " a string " "a string " " a string" "a string"
Factor
<lang factor>USE: unicode " test string " [ blank? ] trim ! leading and trailing " test string " [ blank? ] trim-head ! only leading " test string " [ blank? ] trim-tail ! only trailing</lang>
Forth
Modern Forth advocates the use of "stack strings". These are simply the memory address of the text on the stack followed by the length of the string on the stack. The advantage of using stack strings is that string manipulation is done without resorting to copying the strings to temporary memory. This makes string manipulation very fast. The values left on the stack are suitable as input arguments for further processing so function concatenation is possible to create more complex functions.
After the string processing is completed on the stack the program can print or copy back to memory as required.
<lang forth>: -leading ( addr len -- addr' len' ) \ called "minus-leading"
begin
over c@ bl = \ fetch character at addr, test if blank (space)
while
\ cut 1 leading character by incrementing address & decrementing length
1 /string \ "cut-string"
repeat ;</lang>
The counterpart function "-trailing" is normally part of a standard forth system, so by concatenating both we create a "STRIP" function. <lang> : strip ( addr len -- addr' len') -leading -trailing ; </lang> Test at the Forth console
: mystring s" Trim this string. " ; mstring type Trim this string. ok mstring -leading type Trim this string. ok mystring -trailing type Trim this string. ok mytring strip type Trim this string. ok
Fortran
The problem is that Fortran does not offer a "string" type, which is to say a store of characters plus a current length. Leaving aside later Fortrans where one can create a data type and associated operations, one must deal with CHARACTER style items, though they were not available in early Fortran. Thus, CHARACTER*(60) TEXT creates a variable capable of storing sixty characters and there is no "varying" attribute as in pl/i to signify a current length as well. The intrinsic function LEN(TEXT) returns 60, so it is really the "size" function. Functions can return CHARACTER types, but, only of a specified size, fixed at compile time. It is common then to have many trailing spaces in such variables. An expression TEXT(start:stop) means select characters start to stop of TEXT.
A function LEN_TRIM(x) may be supplied, returning the index of the last non-blank character. And only of spaces: tabs and suchlike are not blanks. Thus, to remove trailing spaces, TEXT(1:LEN_TRIM(TEXT)) would do the trick. There may also be available an intrinsic function TRIM, which removes leading and trailing spaces, thus TRIM(TEXT) and which does so for any length of TEXT and any length of result, unlike user-written functions that have a fixed result length.
Otherwise, one must write integer functions such as ISTNB(x) and LSTNB(x) to return the first and last non-blank character of x and use them in something like TEXT(ISTNB(TEXT):LSTNB(TEXT)) wherever one wants the trimmed content of TEXT. Correspondingly TEXT(ISTNB(TEXT):LEN(TEXT)) to omit leading spaces and TEXT(1:LSTNB(TEXT)) to omit trailing spaces. Such user-written functions can make their own choices about tabs and any other special characters.
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Const whitespace = !" \t\n\v\f\r"
Dim s As String = !" \tRosetta Code \v\f\r\n" Dim s1 As String = LTrim (s, Any whitespace) Dim s2 As String = RTrim (s, Any whitespace) Dim s3 As String = Trim (s, Any whitespace)
' Under Windows console : ' "vertical tab" displays as ♂ ' "form feed" displays as ♀ ' the other whitespace characters do what it says on the tin
Print "Untrimmed" , "=> "; s Print "Left Trimmed" , "=> "; s1 Print "Right Trimmed" , "=> "; s2 Print "Fully Trimmed" , "=> "; s3 Print Print "Untrimmed" , "=> Length = "; Len(s) Print "Left trimmed" , "=> Length = "; Len(s1) Print "Right trimmed" , "=> Length = "; Len(s2) Print "Fully trimmed" , "=> Length = "; Len(s3) Sleep</lang>
- Output:
Untrimmed => Rosetta Code ♂♀ Left Trimmed => Rosetta Code ♂♀ Right Trimmed => Rosetta Code Fully Trimmed => Rosetta Code Untrimmed => Length = 20 Left trimmed => Length = 17 Right trimmed => Length = 15 Fully trimmed => Length = 12
Gambas
Click this link to run this code <lang gambas>Public Sub Main() Dim sString As String = " Hello world! "
Print sString & "\tString length = " & Len(sString) & " - Original string" Print LTrim(sString) & "\tString length = " & Len(LTrim(sString)) & " - String with leading whitespace removed" Print RTrim(sString) & "\tString length = " & Len(RTrim(sString)) & " - String with trailing whitespace removed" Print Trim(sString) & "\t\tString length = " & Len(Trim(sString)) & " - String with both leading and trailing whitespace removed"
End</lang> Output:
Hello world! String length = 20 - Original string
Hello world! String length = 16 - String with leading whitespace removed
Hello world! String length = 16 - String with trailing whitespace removed
Hello world! String length = 12 - String with both leading and trailing whitespace removed
Go
<lang go>package main
import (
"fmt" "strings" "unicode"
)
var simple = `
simple `
func main() {
show("original", simple)
show("leading ws removed", strings.TrimLeftFunc(simple, unicode.IsSpace))
show("trailing ws removed", strings.TrimRightFunc(simple, unicode.IsSpace))
// equivalent to strings.TrimFunc(simple, unicode.IsSpace)
show("both removed", strings.TrimSpace(simple))
}
func show(label, str string) {
fmt.Printf("%s: |%s| %v\n", label, str, []rune(str))
}</lang> Example text is shows a leading linefeed and tab, and three trailing spaces. The code uses the Unicode definition of whitespace. Other defintions could be implemented with a custom function given to TrimXFunc.
Output below shows the text surrounded by vertical bars to show the extent of whitespace, followed by a list of the character values in the string, to show exactly what whitespace is present.
original: |
simple | [10 9 115 105 109 112 108 101 32 32 32]
leading ws removed: |simple | [115 105 109 112 108 101 32 32 32]
trailing ws removed: |
simple| [10 9 115 105 109 112 108 101]
both removed: |simple| [115 105 109 112 108 101]
Groovy
Solution uses StringUtils class from Apache Commons "Lang" library: <lang groovy>//Grape setup to get library @Grab('org.apache.commons:commons-lang3:3.0.1') import static org.apache.commons.lang3.StringUtils.*
def abc = '\r\n\t abc \r\n\t'
def printTest = {
println ('|' + it + '|')
}
println 'Unstripped\n------------' printTest abc
println '============\n\nStripped\n------------' printTest strip(abc)
println '============\n\nLeft Stripped\n------------' printTest stripStart(abc, null)
println '============\n\nRight Stripped\n------------' printTest stripEnd(abc, null) println '============'</lang>
- Output:
Unstripped ------------ | abc | ============ Stripped ------------ |abc| ============ Left Stripped ------------ |abc | ============ Right Stripped ------------ | abc| ============
Haskell
<lang haskell>import Data.Char (isSpace) import Data.List (dropWhileEnd)
trimLeft :: String -> String trimLeft = dropWhile isSpace
trimRight :: String -> String trimRight = dropWhileEnd isSpace
trim :: String -> String trim = trimLeft . trimRight</lang>
Icon and Unicon
This solution takes the phrase "other such characters that have no corresponding graphical representation" quite literallly. <lang Unicon>procedure main()
unp := &cset[1+:32]++' \t'++&cset[127:0] # all 'unprintable' chars
s := " Hello, people of earth! "
write("Original: '",s,"'")
write("leading trim: '",reverse(trim(reverse(s),unp)),"'")
write("trailing trim: '",trim(s,unp),"'")
write("full trim: '",reverse(trim(reverse(trim(s,unp)),unp)),"'")
end</lang>
- Sample run:
->trim Original: ' Hello, people of earth! ' leading trim: 'Hello, people of earth! ' trailing trim: ' Hello, people of earth!' full trim: 'Hello, people of earth!' ->
J
Note: The quote verb is only used to enclose the resulting string in single quotes so the beginning and end of the new string are visible.
<lang j> require 'strings' NB. the strings library is automatically loaded in versions from J7 on
quote dlb ' String with spaces ' NB. delete leading blanks
'String with spaces '
quote dtb ' String with spaces ' NB. delete trailing blanks
' String with spaces'
quote dltb ' String with spaces ' NB. delete leading and trailing blanks
'String with spaces'</lang>
In addition deb (delete extraneous blanks) will trim both leading and trailing blanks as well as replace consecutive spaces within the string with a single space.
<lang j> quote deb ' String with spaces ' NB. delete extraneous blanks
'String with spaces'</lang>
These existing definitions can be easily amended to include whitespace other than spaces if desired.
<lang j>whpsc=: ' ',TAB NB. define whitespace as desired
dlws=: }.~ (e.&whpsc i. 0:) NB. delete leading whitespace (spaces and tabs)
dtws=: #~ ([: +./\. -.@:e.&whpsc) NB. delete trailing whitespace
dltws=: #~ ([: (+./\ *. +./\.) -.@:e.&whpsc) NB. delete leading & trailing whitespace
dews=: #~ (+. (1: |. (> </\)))@(-.@:e.&whpsc) NB. delete extraneous whitespace</lang>
Java
Java offers String.trim. However, this function only strips out ASCII control characters. As such it should generally be avoided for processing text.
Rather, the function Character.isWhitespace should be used to strip out any Unicode whitespaces. Note that the Java implementation slightly deviates from the strict Unicode definition: For example, non-breaking spaces are not considered whitespace by Java. This is fine for stripping leading/trailing whitespaces, as a non-breaking space generally should not appear there, but is something to keep in mind.
Left trim and right trim taken from here.
<lang java>public class Trims{
public static String ltrim(String s) {
int i = 0;
while (i < s.length() && Character.isWhitespace(s.charAt(i))){
i++;
}
return s.substring(i);
}
public static String rtrim(String s) {
int i = s.length() - 1;
while (i > 0 && Character.isWhitespace(s.charAt(i))){
i--;
}
return s.substring(0, i + 1);
}
public static String trim(String s) {
return rtrim(ltrim(s));
}
public static void main(String[] args){
String s = " \t \r \n String with spaces \u2009 \t \r \n ";
System.out.printf("[%s]\n", ltrim(s));
System.out.printf("[%s]\n", rtrim(s));
System.out.printf("[%s]\n", trim(s));
}
}</lang>
JavaScript
<lang javascript>{
let s = " \t String with spaces \t ";
// a future version of ECMAScript will have trimStart(). Some current
// implementations have trimLeft().
console.log("original: '" + s + "'");
console.log("trimmed left: '" + s.replace(/^\s+/,) + "'");
// a future version of ECMAScript will have trimEnd(). Some current
// implementations have trimRight().
console.log("trimmed right: '" + s.replace(/\s+$/,) + "'");
console.log("trimmed both: '" + s.trim() + "'");
}</lang>
- Output:
original: ' String with spaces ' trimmed left: 'String with spaces ' trimmed right: ' String with spaces' trimmed both: 'String with spaces'
Or, composing from generic primitives:
<lang JavaScript>(() => {
'use strict';
// stripStart :: Text -> Text let stripStart = s => dropWhile(isSpace, s);
// stripEnd :: Text -> Text let stripEnd = s => dropWhileEnd(isSpace, s);
// strip :: Text -> Text let strip = s => dropAround(isSpace, s); // OR: let strip = s => s.trim();
// GENERIC FUNCTIONS
// dropAround :: (Char -> Bool) -> Text -> Text let dropAround = (p, s) => dropWhile(p, dropWhileEnd(p, s));
// dropWhile :: (a -> Bool) -> [a] -> [a]
let dropWhile = (p, xs) => {
for (var i = 0, lng = xs.length;
(i < lng) && p(xs[i]); i++) {}
return xs.slice(i);
}
// dropWhileEnd :: (Char -> Bool) -> Text -> Text
let dropWhileEnd = (p, s) => {
for (var i = s.length; i-- && p(s[i]);) {}
return s.slice(0, i + 1);
}
// isSpace :: Char -> Bool let isSpace = c => /\s/.test(c);
// show :: a -> String let show = x => JSON.stringify(x, null, 2);
// TEST
let strText = " \t\t \n \r Much Ado About Nothing \t \n \r ";
return show([stripStart, stripEnd, strip]
.map(f => '-->' + f(strText) + '<--'));
})(); </lang>
- Output:
[ "-->Much Ado About Nothing \t \n \r <--", "--> \t\t \n \r Much Ado About Nothing<--", "-->Much Ado About Nothing<--" ]
jq
Recent versions of jq (since July 2014) support PCRE regex operations; \p{_} character classes are also supported. The following accordingly uses \p{Cc} as that corresponds to ASCII 0x00–0x1F.
Notice that since jq strings are JSON strings, one must, for example, write "\\s" for the regex '\s'. <lang jq>def lstrip: sub( "^[\\s\\p{Cc}]+"; "" );
def rstrip: sub( "[\\s\\p{Cc}]+$"; "" );
def strip: lstrip | rstrip;</lang> Examples: <lang jq>def demo:
"lstrip: \(lstrip)", "rstrip: \(rstrip)", "strip: \(strip)" ;
(" \t \r \n String with spaces \t \r \n ",
"� <- control A", "\u0001 \u0002 <- ^A ^B"
) | demo </lang>
- Output:
<lang sh>$ jq -n -f Strip_whitespace_top_tail.jq "lstrip: String with spaces \t \r \n " "rstrip: \t \r \n String with spaces" "strip: String with spaces" "rstrip: \u0001 <- control A" "strip: <- control A" "lstrip: <- ^A ^B" "rstrip: \u0001 \u0002 <- ^A ^B" "strip: <- ^A ^B"</lang>
Jsish
Using echo-mode unitTest lines. Lines starting with semicolon are echoed and captured during test.
<lang javascript>#!/usr/bin/env jsish /* Strip whitespace from string, in Jsi */ var str = ' \n \t String with whitespace \t \n ';
- 'Original';
- str;
- 'Default trim characters are space, tab, newline, carriage return';
- 'trimLeft, remove leading characters';
- str.trimLeft();
- 'trimRight, remove trailing characters';
- str.trimRight();
- 'trim, removes leading and trailing';
- str.trim();
/*
!EXPECTSTART!
'Original' str ==>
String with whitespace
'Default trim characters are space, tab, newline, carriage return' 'trimLeft, remove leading characters' str.trimLeft() ==> String with whitespace
'trimRight, remove trailing characters' str.trimRight() ==>
String with whitespace
'trim, removes leading and trailing' str.trim() ==> String with whitespace
!EXPECTEND!
- /</lang>
- Output:
prompt$ jsish -u stripWhitespace.jsi
[PASS] stripWhitespace.jsi
prompt$ jsish --U stripWhitespace.jsi
'Original'
str ==>
String with whitespace
'Default trim characters are space, tab, newline, carriage return'
'trimLeft, remove leading characters'
str.trimLeft() ==> String with whitespace
'trimRight, remove trailing characters'
str.trimRight() ==>
String with whitespace
'trim, removes leading and trailing'
str.trim() ==> String with whitespace
Julia
<lang julia>julia> s = " \t \r \n String with spaces \t \r \n " " \t \r \n String with spaces \t \r \n "
julia> lstrip(s) "String with spaces \t \r \n "
julia> rstrip(s) " \t \r \n String with spaces"
julia> strip(s) "String with spaces"</lang>
Kotlin
It is worth poiting out that Kotlin, unlike Java, has String.trimStart and String.trimEnd. More importantly though, Kotlin’s String.trim actually trims whitespace as defined by Unicode, whereas Java’s just strips Unicode control characters.
<lang kotlin>fun main(args: Array<String>) {
val s = " \tRosetta Code \r \u2009 \n"
println("Untrimmed => [$s]")
println("Left Trimmed => [${s.trimStart()}]")
println("Right Trimmed => [${s.trimEnd()}]")
println("Fully Trimmed => [${s.trim()}]")
}</lang>
- Output:
Untrimmed => [ Rosetta Code ] Left Trimmed => [Rosetta Code ] Right Trimmed => [ Rosetta Code] Fully Trimmed => [Rosetta Code]
Lambdatalk
<lang scheme> initial string : {def string ___String with "_" displaying space_____}
-> string ___String with "_" displaying space_____
trimLeft : {S.replace ^_+ by in {string}}
-> String with "_" displaying space_____
trimRight : {S.replace _+$ by in {string}}
-> ___String with "_" displaying space
trimBoth : {S.replace _+$ by in {S.replace ^_+ by in {string}}}
-> String with "_" displaying space
</lang>
Lasso
Note that the example below uses the retarget operator ("&") to output as the trim method modifies the string in place.
The '>' and '<' strings have been included in this example to demonstrate the whitespace trim. <lang Lasso>// String with leading whitespace removed '>' + (' \t Hello')->trim& + '<'
// String with trailing whitespace removed '>' + ('Hello \t ')->trim& + '<'
// String with both leading and trailing whitespace removed '>' + (' \t Hello \t ')->trim& + '<'</lang>
Liberty BASIC
<lang lb>a$=" This is a test "
'LB TRIM$ removes characters with codes 0..31 as well as a space(code 32) 'So these versions of ltrim rtrim remove them too 'a$=" "+chr$(31)+"This is a test"+chr$(31)+" "
print "Source line" print ">";a$;"<" print "Strip left" print ">";ltrim$(a$);"<" print "Strip right" print ">";rtrim$(a$);"<" print "Strip both" print ">";trim$(a$);"<"
end
function ltrim$(a$)
c$=trim$(a$+".") ltrim$ = mid$(c$, 1, len(c$)-1)
end function
function rtrim$(a$)
c$=trim$("."+a$)
rtrim$ = mid$(c$, 2)
end function
</lang>
Logtalk
Using atoms for representing strings and assuming an ASCII text encoding: <lang logtalk>
- - object(whitespace).
:- public(trim/4).
trim(String, TrimLeft, TrimRight, TrimBoth) :-
trim_left(String, TrimLeft),
trim_right(String, TrimRight),
trim_right(TrimLeft, TrimBoth).
trim_left(String, TrimLeft) :-
atom_codes(String, Codes),
trim(Codes, TrimCodes),
atom_codes(TrimLeft, TrimCodes).
trim_right(String, TrimRight) :-
atom_codes(String, Codes),
list::reverse(Codes, ReverseCodes),
trim(ReverseCodes, ReverseTrimCodes),
list::reverse(ReverseTrimCodes, TrimCodes),
atom_codes(TrimRight, TrimCodes).
trim([], []).
trim([InCode| InCodes], OutCodes) :-
( InCode =< 32 ->
trim(InCodes, OutCodes)
; OutCodes = [InCode| InCodes]
).
- - end_object.
</lang> Sample output: <lang text> | ?- whitespace::trim('\n\t Rosetta Code \t\n', TrimLeft, TrimRight, TrimBoth). TrimLeft = 'Rosetta Code \t\n', TrimRight = '\n\t Rosetta Code', TrimBoth = 'Rosetta Code' yes </lang>
Lua
<lang lua>str = " \t \r \n String with spaces \t \r \n "
print( string.format( "Leading whitespace removed: %s", str:match( "^%s*(.+)" ) ) ) print( string.format( "Trailing whitespace removed: %s", str:match( "(.-)%s*$" ) ) ) print( string.format( "Leading and trailing whitespace removed: %s", str:match( "^%s*(.-)%s*$" ) ) )</lang>
M2000 Interpreter
<lang M2000 Interpreter> Module CheckIt { filter$=chr$(0) for i=1 to 31:filter$+=chr$(i):next a$=chr$(9)+" There are unwanted blanks here! "+chr$(9) a$=filter$(a$,filter$) ' exclude non printable characters
\\ string encoded as UTF16LE Print Len(a$)=39 Print(ltrim$(a$)) Print(rtrim$(a$)) Print(trim$(a$)) \\ string encoded as ANSI base to Locale oldlocale=Locale Locale 1033 a$=str$(a$) Print Len(a$)=19.5 ' unit for length is a word (2 bytes), so 19.5 means 19.5*2 bytes= 39 bytes PrintAnsi(ltrim$(a$ as byte)) PrintAnsi(rtrim$(a$ as byte)) PrintAnsi(trim$(a$ as byte)) Locale oldlocale Sub Print(a$) Print "*"+a$+"*" End Sub Sub PrintAnsi(a$) Print "*"+chr$(a$)+"*" End Sub } Checkit </lang>
- Output:
True
*There are unwanted blanks here! *
* There are unwanted blanks here!*
*There are unwanted blanks here!*
True
*There are unwanted blanks here! *
* There are unwanted blanks here!*
*There are unwanted blanks here!*
Maple
<lang Maple>str := " \t \r \n String with spaces \t \r \n ";
with(StringTools):
TrimLeft(str); TrimRight(str); Trim(str);</lang>
Mathematica
<lang Mathematica>StringTrim[" \n\t string with spaces \n \t "]</lang>
MATLAB / Octave
<lang matlab>% remove trailing whitespaces
str = str(1:find(~isspace(str),1,'last'));
% remove leading whitespaces
str = str(find(~isspace(str),1):end);
% removes leading and trailing whitespaces, vectorized version
f = ~isspace(str); str = str(find(f,1,'first'):find(f,1,'last');
% a built-in function, removes leading and trailing whitespaces
str = strtrim(str);</lang>
Mercury
<lang mercury>:- module top_and_tail.
- - interface.
- - import_module io.
- - pred main(io::di, io::uo) is det.
- - implementation.
- - import_module list, string.
main(!IO) :-
TestPhrase = "\t\r\n String with spaces \t\r\n ",
io.format("leading ws removed: %s\n", [s(lstrip(TestPhrase))], !IO),
io.format("trailing ws removed: %s\n", [s(rstrip(TestPhrase))], !IO),
io.format("both removed: %s\b", [s(strip(TestPhrase))], !IO).</lang>
Nemerle
<lang Nemerle>def str = "\t\n\t A string with\nwhitespace\n\n\t "; WriteLine(str.TrimStart()); WriteLine(str.TrimEnd()); WriteLine(str.Trim()); // both ends at once, of course, internal whitespace is preserved in all 3</lang>
NetRexx
NetRexx provides a strip() method which can be used to remove all of a single character from the head and/or tail of a string. To remove all whitespace characters from a string requires a little more work: <lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols nobinary
runSample(arg) return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method stripWhitespace(sstring, soption = 'BOTH') public static
wsChars = getWhitspaceCharacterString()
po1 = sstring.verify(wsChars)
if po1 = 0 then do
sstring =
end
else do
po2 = sstring.length - (sstring.reverse().verify(wsChars) - 1) + 1
ss = sstring
parse ss sl =(po1) sm =(po2) st
if po1 <= 1 then sl =
soption = soption.upper()
select
when 'BOTH'.abbrev(soption, 1) then sstring = sm
when 'LEADING'.abbrev(soption, 1) then sstring = sm || st
when 'TRAILING'.abbrev(soption, 1) then sstring = sl || sm
otherwise sstring = sm
end
end
return sstring
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /**
* Create an array containing a useful subset of unicode whitespace characters * * @return an array of unicode whitespace characters * @see http://www.fileformat.info/info/unicode/category/index.htm */
method getWhitspaceCharacters() public static returns Rexx[]
wsChars = [ - /* LINE SEPARATOR [Zi] */ '\u2028', /* PARAGRAPH SEPARATOR [Zp] */ '\u2029', - /* SPACE [Zs] */ '\u0020', /* NO-BREAK SPACE [Zs] */ '\u00A0', - /* OGHAM SPACE MARK [Zs] */ '\u1680', /* MONGOLIAN VOWEL SEPARATOR [Zs] */ '\u180E', - /* EN QUAD [Zs] */ '\u2000', /* EM QUAD [Zs] */ '\u2001', - /* EN SPACE [Zs] */ '\u2002', /* EM SPACE [Zs] */ '\u2003', - /* THREE-PER-EM SPACE [Zs] */ '\u2004', /* FOUR-PER-EM SPACE [Zs] */ '\u2005', - /* SIX-PER-EM SPACE [Zs] */ '\u2006', /* FIGURE SPACE [Zs] */ '\u2007', - /* PUNCTUATION SPACE [Zs] */ '\u2008', /* THIN SPACE [Zs] */ '\u2009', - /* HAIR SPACE [Zs] */ '\u200A', /* NARROW NO-BREAK SPACE [Zs] */ '\u202F', - /* MEDIUM MATHEMATICAL SPACE [Zs] */ '\u3000', /* IDIOGRAPHIC SPACE [Zs] */ '\u205F', - /* BACKSPACE [Cc] */ '\u0008', /* CHARACTER TABULATION, HT [Cc] */ '\u0009', - /* LINE FEED (LF) [Cc] */ '\u000A', /* LINE TABULATION (VT) [Cc] */ '\u000B', - /* FORM FEED (FF) [Cc] */ '\u000C', /* CARRIAGE RETURN (CR) [Cc] */ '\u000D', - /* INFORMATION SEPARATOR FOUR [Cc] */ '\u001C', /* INFORMATION SEPARATOR THREE [Cc] */ '\u001D', - /* INFORMATION SEPARATOR TWO [Cc] */ '\u001E', /* INFORMATION SEPARATOR ONE [Cc] */ '\u001F', - /* NEXT LINE (NEL) [Cc] */ '\u0085', - /* ZERO WIDTH SPACE [Cf] */ '\u200B', /* ZERO WIDTH NO-BREAK SPACE [Cf] */ '\uFEFF' - ] return wsChars
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method getWhitspaceCharacterString() public static returns Rexx
wsCharstring = loop wsChar over getWhitspaceCharacters() wsCharstring = wsCharstring || wsChar end wsChar return wsCharstring
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method runSample(arg) public static
sstrings = [ -
' \u0020 \u0009 \u000D\r \n \u2029\uFEFF1 String with white space. \t \r \n \u1680 ', -
' \t 2 String with white space. \t ', -
'3 String with white space. \t', -
' \t 4 String with white space.', -
'5 String with white space.', -
'\u0020\u0009\u2029\uFEFF\u1680\u2006', -
' ', -
-
]
loop sstringO over sstrings
sstringL = stripWhitespace(sstringO, 'l')
sstringT = stripWhitespace(sstringO, 't')
sstringB = stripWhitespace(sstringO)
say ' Original string ['sstringO']'
say ' strip leading ['sstringL']'
say ' strip trailing ['sstringT']'
say ' strip both ['sstringB']'
say
end sstringO
return
</lang> Output:
Original string [
1 String with white space.
]
strip leading [1 String with white space.
]
strip trailing [
1 String with white space.]
strip both [1 String with white space.]
Original string [ 2 String with white space. ]
strip leading [2 String with white space. ]
strip trailing [ 2 String with white space.]
strip both [2 String with white space.]
Original string [3 String with white space. ]
strip leading [3 String with white space. ]
strip trailing [3 String with white space.]
strip both [3 String with white space.]
Original string [ 4 String with white space.]
strip leading [4 String with white space.]
strip trailing [ 4 String with white space.]
strip both [4 String with white space.]
Original string [5 String with white space.]
strip leading [5 String with white space.]
strip trailing [5 String with white space.]
strip both [5 String with white space.]
Original string [
]
strip leading []
strip trailing []
strip both []
Original string [ ]
strip leading []
strip trailing []
strip both []
Original string []
strip leading []
strip trailing []
strip both []
NewLISP
<lang NewLISP>(setq str " this is a string ")
- trim leading blanks
(trim str " " "")
- trim trailing blanks
(trim str "" " ")
- trim both leading and trailing blanks
(trim str)</lang>
Nim
<lang nim>import strutils
let s = " \t \n String with spaces \t \n " echo "'", s, "'" echo "'", s.strip(trailing = false), "'" echo "'", s.strip(leading = false), "'" echo "'", s.strip(), "'"</lang>
Oberon-2
Oxford Oberon-2 <lang oberon2> MODULE Trim; IMPORT Out,Strings,SYSTEM;
CONST (* whitespaces *) HT = 09X; VT = 0BX; FF = 0CX; GS = 1DX; US = 1FX; LF = 0AX; CR = 0DX; FS = 1CX; RS = 1EX; SPC = 20X;
PROCEDURE LTrim(VAR s: ARRAY OF CHAR); VAR j : INTEGER; BEGIN j := 0; WHILE (s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR (s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR (s[j] = RS) OR (s[j] = US) OR (s[j] = SPC) DO INC(j) END; SYSTEM.MOVE(SYSTEM.ADR(s[j]),SYSTEM.ADR(s[0]),LEN(s) - j); END LTrim;
PROCEDURE RTrim(VAR s: ARRAY OF CHAR); VAR j : INTEGER; BEGIN j := LEN(s) - 1; WHILE (j >= 0) & (s[j] = 0X) DO DEC(j) END; WHILE (j >= 0) & ((s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR (s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR (s[j] = RS) OR (s[j] = US) OR (s[j] = SPC)) DO s[j] := 0X;
DEC(j)
END END RTrim;
PROCEDURE Trim(VAR s: ARRAY OF CHAR); BEGIN LTrim(s); RTrim(s) END Trim;
VAR s: ARRAY 100 OF CHAR;
BEGIN s := " A AAA"; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; s := "AAA A "; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; s := " A AA A "; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; s := " "; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; s := " "; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; s := " "; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln; END Trim. </lang> Output:
[ A AAA]= [A AAA] [AAA A ]= [AAA A] [ A AA A ]= [A AA A] [ ]= [] [ ]= [] [ ]= [] []= [] []= []
Objective-C
<lang objc>#import <Foundation/Foundation.h>
@interface NSString (RCExt) -(NSString *) ltrim; -(NSString *) rtrim; -(NSString *) trim; @end
@implementation NSString (RCExt) -(NSString *) ltrim {
NSInteger i;
NSCharacterSet *cs = [NSCharacterSet whitespaceAndNewlineCharacterSet];
for(i = 0; i < [self length]; i++)
{
if ( ![cs characterIsMember: [self characterAtIndex: i]] ) break;
}
return [self substringFromIndex: i];
}
-(NSString *) rtrim {
NSInteger i;
NSCharacterSet *cs = [NSCharacterSet whitespaceAndNewlineCharacterSet];
for(i = [self length] -1; i >= 0; i--)
{
if ( ![cs characterIsMember: [self characterAtIndex: i]] ) break;
}
return [self substringToIndex: (i+1)];
}
-(NSString *) trim {
return [self
stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]; } @end
int main() {
@autoreleasepool {
NSString *s = @" this is a string ";
NSLog(@"'%@'", s); NSLog(@"'%@'", [s ltrim]); NSLog(@"'%@'", [s rtrim]); NSLog(@"'%@'", [s trim]);
} return 0;
}</lang>
OCaml
<lang ocaml>let left_pos s len =
let rec aux i = if i >= len then None else match s.[i] with | ' ' | '\n' | '\t' | '\r' -> aux (succ i) | _ -> Some i in aux 0
let right_pos s len =
let rec aux i = if i < 0 then None else match s.[i] with | ' ' | '\n' | '\t' | '\r' -> aux (pred i) | _ -> Some i in aux (pred len)
let trim s =
let len = String.length s in match left_pos s len, right_pos s len with | Some i, Some j -> String.sub s i (j - i + 1) | None, None -> "" | _ -> assert false
let ltrim s =
let len = String.length s in match left_pos s len with | Some i -> String.sub s i (len - i) | None -> ""
let rtrim s =
let len = String.length s in match right_pos s len with | Some i -> String.sub s 0 (i + 1) | None -> ""</lang>
we put the previous code in a file called "trim.ml", and then we test these functions in the toplevel:
$ ocaml # #use "trim.ml" ;; val left_pos : string -> int -> int option = <fun> val right_pos : string -> int -> int option = <fun> val trim : string -> string = <fun> val ltrim : string -> string = <fun> val rtrim : string -> string = <fun> # let s = " \t \r \n String with spaces \t \r \n " ;; val s : string = " \t \r \n String with spaces \t \r \n " # trim s ;; - : string = "String with spaces" # ltrim s ;; - : string = "String with spaces \t \r \n " # rtrim s ;; - : string = " \t \r \n String with spaces"
Since OCaml version 4.00.0 there is a function String.trim.
OpenEdge/Progress
<lang progress>DEF VAR cc AS CHAR INIT " string with spaces ".
MESSAGE
"|" + LEFT-TRIM( cc ) + "|" SKIP "|" + RIGHT-TRIM( cc ) + "|" SKIP "|" + TRIM( cc ) + "|"
VIEW-AS ALERT-BOX.</lang>
- Output:
--------------------------- Message --------------------------- |string with spaces | | string with spaces| |string with spaces| --------------------------- OK ---------------------------
Perl
<lang perl>sub ltrim { shift =~ s/^\s+//r } sub rtrim { shift =~ s/\s+$//r } sub trim { ltrim rtrim shift }
- Usage:
my $p = " this is a string "; print "'", $p, "'\n"; print "'", trim($p), "'\n"; print "'", ltrim($p), "'\n"; print "'", rtrim($p), "'\n";</lang>
Phix
<lang Phix>constant s = "\ttest\n" ?s ?trim_head(s) ?trim_tail(s) ?trim(s)</lang>
- Output:
"\ttest\n" "test\n" "\ttest" "test"
PHP
There is a built-in function that already does this. <lang PHP><?php
/**
* @author Elad Yosifon */
$string = ' this is a string '; echo '^'.trim($string) .'$'.PHP_EOL; echo '^'.ltrim($string).'$'.PHP_EOL; echo '^'.rtrim($string).'$'.PHP_EOL; </lang>
- Output:
^this is a string$ ^this is a string $ ^ this is a string$
PicoLisp
<lang PicoLisp>(de trimLeft (Str)
(pack (flip (trim (flip (chop Str))))) )
(de trimRight (Str)
(pack (trim (chop Str))) )
(de trimBoth (Str)
(pack (clip (chop Str))) )</lang>
Test:
: (trimLeft " ^G ^I trimmed left ^L ") -> "trimmed left ^L " : (trimRight " ^G ^I trimmed right ^L ") -> " ^G ^I trimmed right" : (trimBoth " ^G ^I trimmed both ^L ") -> "trimmed both"
PL/I
<lang pli>put ( trim(text, ' ', ) ); /* trims leading blanks. */ put ( trim(text, , ' ') ); /* trims trailing blanks. */ put ( trim(text) ); /* trims leading and trailing */
/* blanks. */</lang>
To remove any white-space character(s) in a portable way:- <lang pli>declare whitespace character(33) value
((substr(collate(), 1, 32) || ' '));
put ( trim(text, whitespace) ); /* trims leading white space. */ put ( trim(text, , whitespace) ); /* trims trailing white space. */ put ( trim(text, whitespace, whitespace) );
/* trims leading and trailing */
/* white space. */</lang>
PowerShell
<lang PowerShell> $var = " Hello World " $var.TrimStart() # String with leading whitespace removed $var.TrimEnd() # String with trailing whitespace removed $var.Trim() # String with both leading and trailing whitespace removed </lang> Output:
Hello World Hello World Hello World
Prolog
Works with SWI-Prolog. <lang Prolog>strip :- In = " There are unwanted blanks here! ", strip_left(In, OutLeft), format('In : ~s__~n', [In]), format('Strip left : ~s__~n', [OutLeft]), strip_right(In, OutRight), format('Strip right : ~s__~n', [OutRight]), strip(In, Out), format('Strip : ~s__~n', [Out]).
strip_left(In, Out) :-
strip_action(In, Out, []).
strip_right(In, Out) :- reverse(In, RIn), strip_left(RIn, ROut), reverse(ROut, Out).
strip(In, Out) :- strip_left(In, Tmp), strip_right(Tmp, Out).
strip_action([X|T]) --> {\+code_type(X, graph), !}, strip_action(T).
strip_action(X) --> X.
</lang>
Output :
?- strip. In : There are unwanted blanks here! __ Strip left : There are unwanted blanks here! __ Strip right : There are unwanted blanks here!__ Strip : There are unwanted blanks here!__ true.
SWI-Prolog has an integrated version of strip : normalize_space(-Out, +In)
?- In = ' There are unwanted blanks here! ', normalize_space(atom(Out), In). In = ' There are unwanted blanks here! ', Out = 'There are unwanted blanks here!'.
alternative using DCG strings
<lang prolog>
- - system:set_prolog_flag(double_quotes,chars) .
strip_leading(INPUTz,OUTPUTz)
- -
prolog:phrase(strip_leading(OUTPUTz),INPUTz) .
strip_trailing(INPUTz,OUTPUTz)
- -
prolog:phrase(strip_trailing(OUTPUTz),INPUTz) .
strip_leading_and_trailing(INPUTz,OUTPUTz)
- -
prolog:phrase(strip_leading_and_trailing(OUTPUTz),INPUTz) .
strip_leading(OUTPUTz) --> strip_leading_spacious , strip_leading_nonspacious(OUTPUTz) .
strip_trailing(OUTPUTz) --> strip_trailing_nonspacious(OUTPUTz) , strip_trailing_spacious .
strip_leading_and_trailing(OUTPUTz) --> strip_leading_spacious , strip_trailing_nonspacious(OUTPUTz) , strip_trailing_spacious .
strip_leading_spacious --> [CHAR] , { prolog:char_type(CHAR,space) } , ! , strip_leading_spacious .
strip_leading_spacious --> [] .
strip_leading_nonspacious([OUTPUT|OUTPUTz]) --> [OUTPUT] , ! , strip_leading_nonspacious(OUTPUTz) .
strip_leading_nonspacious([]) --> [] .
strip_trailing_nonspacious([OUTPUT|OUTPUTz]) --> \+ strip_trailing_spacious , [OUTPUT] , ! , strip_trailing_nonspacious(OUTPUTz) .
strip_trailing_nonspacious([]) --> [] .
strip_trailing_spacious --> [CHAR] , { prolog:char_type(CHAR,space) } , ! , strip_trailing_spacious .
strip_trailing_spacious --> \+ [_] % .i.e. at end-of-string . . </lang>
- Output:
/*
?- strip_leading(" Hello World ",OUTPUTz) .
OUTPUTz = ['H', e, l, l, o, ' ', 'W', o, r, l, d, ' '].
?- strip_trailing(" Hello World ",OUTPUTz).
OUTPUTz = [' ', 'H', e, l, l, o, ' ', 'W', o, r, l, d].
?- strip_leading_and_trailing(" Hello World ",OUTPUTz).
OUTPUTz = ['H', e, l, l, o, ' ', 'W', o, r, l, d].
?-
PureBasic
Note, if only spaces need to be removed, PureBasic provides commands that do this: LTrim(), RTrim(), and Trim(). To handle a larger selection of whitespace the following functions meet the task. <lang PureBasic>;define the whitespace as desired
- whitespace$ = " " + Chr($9) + Chr($A) + Chr($B) + Chr($C) + Chr($D) + Chr($1C) + Chr($1D) + Chr($1E) + Chr($1F)
Procedure.s myLTrim(source.s)
Protected i, *ptrChar.Character, length = Len(source)
*ptrChar = @source
For i = 1 To length
If Not FindString(#whitespace$, Chr(*ptrChar\c))
ProcedureReturn Right(source, length + 1 - i)
EndIf
*ptrChar + SizeOf(Character)
Next
EndProcedure
Procedure.s myRTrim(source.s)
Protected i, *ptrChar.Character, length = Len(source)
*ptrChar = @source + (length - 1) * SizeOf(Character)
For i = length To 1 Step - 1
If Not FindString(#whitespace$, Chr(*ptrChar\c))
ProcedureReturn Left(source, i)
EndIf
*ptrChar - SizeOf(Character)
Next
EndProcedure
Procedure.s myTrim(source.s)
ProcedureReturn myRTrim(myLTrim(source))
EndProcedure
If OpenConsole()
PrintN(#DQUOTE$ + myLTrim(" Top ") + #DQUOTE$)
PrintN(#DQUOTE$ + myRTrim(" Tail ") + #DQUOTE$)
PrintN(#DQUOTE$ + myTrim(" Both ") + #DQUOTE$)
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</lang>
- Output:
"Top " " Tail" "Both"
Python
<lang python>>>> s = ' \t \r \n String with spaces \t \r \n ' >>> s ' \t \r \n String with spaces \t \r \n ' >>> s.lstrip() 'String with spaces \t \r \n ' >>> s.rstrip() ' \t \r \n String with spaces' >>> s.strip() 'String with spaces' >>> </lang>
Quackery
As a dialogue in the Quackery shell.
<lang Quackery>/O> [ reverse trim reverse ] is trim-trailing ( $ --> $ ) ... [ trim trim-trailing ] is trim-both-ends ( $ --> $ ) ... $ ' a quick quack ' echo$ say "!" cr ... $ ' a quick quack ' trim echo$ say "!" cr ... $ ' a quick quack ' trim-trailing echo$ say "!" cr ... $ ' a quick quack ' trim-both-ends echo$ say "!" cr ...
a quick quack !
a quick quack !
a quick quack!
a quick quack!
Stack empty.</lang>
R
<lang R>s <- " Ars Longa "
trimws(s) [1] "Ars Longa"
trimws(s, "left") [1] "Ars Longa "
trimws(s, "right") [1] " Ars Longa"</lang>
Racket
<lang Racket>
- lang racket
- Using Racket's `string-trim'
(define str " \n\t foo bar \r\n ")
- both sides
(string-trim str) ; -> "foo bar"
- one side
(string-trim str #:right? #f) ; -> "foo bar \r\n " (string-trim str #:left? #f) ; -> " \n\t foo bar"
- can also normalize spaces
(string-normalize-spaces (string-trim str)) ; -> "foo bar" </lang>
Raku
(formerly Perl 6)
<lang perl6>my $s = "\r\n \t\x2029 Good Stuff \x202F\n"; say $s.trim; say $s.trim.raku; say $s.trim-leading.raku; say $s.trim-trailing.raku;</lang>
- Output:
Good Stuff "Good Stuff" "Good Stuff \n" "\r\n \t Good Stuff"
Red
<lang Red>>> trim/head " remove leading white space " == "remove leading white space " >> trim/tail " remove trailing white space " == " remove trailing white space" >> trim " remove both white spaces " == "remove both white spaces"</lang>
Retro
<lang Retro>'__this_is_a_test___ s:trim-left '__this_is_a_test___ s:trim-right '__this_is_a_test___ s:trim</lang>
REXX
version 1
<lang rexx>/*REXX program demonstrates how to strip leading and/or trailing spaces (blanks). */ yyy=" this is a string that has leading/embedded/trailing blanks, fur shure. " say 'YYY──►'yyy"◄──" /*display the original string + fence. */
/*white space also includes tabs (VT, HT), among other characters.*/
/*all examples in each group are equivalent, only the option's 1st*/
/*character is examined. */
noL=strip(yyy,'L') /*elide any leading white space. */ noL=strip(yyy,"l") /* (the same as the above statement.) */ noL=strip(yyy,'leading') /* " " " " " " */ say 'noL──►'noL"◄──" /*display the string with a title+fence*/
noT=strip(yyy,'T') /*elide any trailing white space. */ noT=strip(yyy,"t") /* (the same as the above statement.) */ noT=strip(yyy,'trailing') /* " " " " " " */ say 'noT──►'noT"◄──" /*display the string with a title+fence*/
noB=strip(yyy) /*elide leading & trailing white space.*/ noB=strip(yyy,) /* (the same as the above statement.) */ noB=strip(yyy,'B') /* " " " " " " */ noB=strip(yyy,"b") /* " " " " " " */ noB=strip(yyy,'both') /* " " " " " " */ say 'noB──►'noB"◄──" /*display the string with a title+fence*/
/*elide leading & trailing white space,*/
noX=space(yyy) /* including white space between words.*/ say 'nox──►'noX"◄──" /*display the string with a title+fence*/
/*stick a fork in it, we're all done. */</lang>
output
YYY──► this is a string that has leading/embedded/trailing blanks, fur shure. ◄── noL──►this is a string that has leading/embedded/trailing blanks, fur shure. ◄── noT──► this is a string that has leading/embedded/trailing blanks, fur shure.◄── noB──►this is a string that has leading/embedded/trailing blanks, fur shure.◄── nox──►this is a string that has leading/embedded/trailing blanks, fur shure.◄──
version 2
<lang rexx>/* REXX ***************************************************************
- 01.1.2012 Walter Pachl taking care of all non-printable chars
- /
pc='abcdefghijklmnopqrstuvwxyz' pc=pc||translate(pc)'äöüÄÖÜß1234567890!"§&/()=?*+#;:_,.-<>^!' x01='01'x s=x01||' Hi '||x01||' there! '||x01 say pc /* all printable characters */ s=x01||' Hi '||x01||' there! '||x01 /* my source string */ Say 's >'s'<' /* show it */ p1=verify(s,pc,'M') /* find first printable char */ sl=substr(s,p1) /* start with it */ Say 'sl>'sl'<' sr=reverse(s) p2=verify(sr,pc,'M') /* find last printable char */ sr=left(s,length(s)-p2+1) /* end with it */ Say 'sr>'sr'<' sb=substr(s,p1,length(s)-p1-p2+1) /* remove leading & trailing */ Say 'sb>'space(sb)'!' /* whitespace */ sa=translate(s,pc,pc!!xrange('00'x,'FF'x)) /* all nonprintable chars */
/* are translated to blanks */
sa=space(sa) /* eliminate them except 1 */ Say 'sa>'sa'<'<' /* between words */ s0=space(sa,0) /* remove all whitespace */ Say 's0>'s0'<'</lang> Output:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZäöüÄÖÜß1234567890!"§&/()=?*+'#;:_,.-<>^! s >� Hi � there! �< sl>Hi � there! �< sr>� Hi � there!< sb>Hi � there!< sa>Hi there!< s0>Hithere!<
Ring
<lang ring> aList = " Welcome to the Ring Programming Language " see aList + nl see trim(aList) + nl </lang>
Ruby
<lang ruby>s = " \t\v\r\n\ffoo bar \t\v\r\n\f" p s p s.lstrip # remove leading whitespaces p s.rstrip # remove trailing whitespaces p s.strip # remove both leading and trailing whitespace </lang>
- Output:
" \t\v\r\n\ffoo bar \t\v\r\n\f" "foo bar \t\v\r\n\f" " \t\v\r\n\ffoo bar" "foo bar"
Run BASIC
<lang runbasic>string$ = " abcdefg "
print " Top:";trim$(string$+"|") ' top left trim print "Bottom:";trim$("|"+string$) ' bottom right trim print " Both:";trim$(string$) ' both left and right end</lang>
Top:abcdefg Bottom: abcdefg Both:abcdefg
Rust
<lang rust>fn main() {
let spaces = " \t\n\x0B\x0C\r \u{A0} \u{2000}\u{3000}";
let string_with_spaces = spaces.to_owned() + "String without spaces" + spaces;
assert_eq!(string_with_spaces.trim(), "String without spaces"); assert_eq!(string_with_spaces.trim_left(), "String without spaces".to_owned() + spaces); assert_eq!(string_with_spaces.trim_right(), spaces.to_owned() + "String without spaces");
}</lang>
Sather
<lang sather>class MAIN is
ltrim(s :STR) :STR is
i ::= 0;
loop while!(i < s.size);
if " \t\f\v\n".contains(s[i]) then
i := i + 1;
else
break!;
end;
end;
return s.tail(s.size - i);
end;
rtrim(s :STR) :STR is
i ::= s.size-1;
loop while!(i >= 0);
if " \t\f\v\n".contains(s[i]) then
i := i - 1;
else
break!;
end;
end;
return s.head(i+1);
end;
trim(s :STR) :STR is
return ltrim(rtrim(s));
end;
main is
p ::= " this is a string ";
#OUT + ltrim(p).pretty + "\n";
#OUT + rtrim(p).pretty + "\n";
#OUT + trim(p).pretty + "\n";
end;
end;</lang>
Scala
<lang scala>def trimLeft(str: String) = str dropWhile(_.isWhitespace)
def trimRight(str: String) = str take (str.lastIndexWhere(!_.isWhitespace) + 1)
def trimRight2(str: String) = trimLeft(str reverse) reverse
def trim(str: String) = str trim
def testTrim() = {
val str = " \u001F String with spaces \t \n \r "
println("original : |" + str + "|")
println("trimLeft : |" + trimLeft(str) + "|")
println("trimRight : |" + trimRight(str) + "|")
println("trimRight2: |" + trimRight2(str) + "|")
println("trim : |" + trim(str) + "|")
}</lang>
- Output:
original : | � String with spaces | trimLeft : |String with spaces | trimRight : | � String with spaces| trimRight2: | � String with spaces| trim : |String with spaces|
Seed7
<lang seed7>$ include "seed7_05.s7i";
const proc: main is func
local const string: testStri is " \t \r \n String with spaces \t \r \n "; begin writeln(ltrim(testStri)); writeln(rtrim(testStri)); writeln(trim(testStri)); end func;</lang>
Sidef
<lang ruby>var s = " \t\v\r\n\ffoo bar \t\v\r\n\f"; say s.strip_beg.dump; # remove leading whitespaces say s.strip_end.dump; # remove trailing whitespaces say s.strip.dump; # remove both leading and trailing whitespace</lang>
- Output:
"foo bar \t\13\r\n\f" " \t\13\r\n\ffoo bar" "foo bar"
Smalltalk
<lang smalltalk>String extend [
ltrim [
^self replacingRegex: '^\s+' with: .
]
rtrim [
^self replacingRegex: '\s+$' with: .
]
trim [
^self ltrim rtrim.
]
]
|a| a := ' this is a string '.
('"%1"' % {a}) displayNl. ('"%1"' % {a ltrim}) displayNl. ('"%1"' % {a rtrim}) displayNl. ('"%1"' % {a trim}) displayNl.</lang>
SNOBOL4
<lang SNOBOL4> s1 = s2 = " Hello, people of earth! "
s2 = CHAR(3) s2 CHAR(134) &ALPHABET TAB(33) . prechars &ALPHABET POS(127) RTAB(0) . postchars stripchars = " " prechars postchars
- TRIM() removes final spaces and tabs:
OUTPUT = "Original: >" s1 "<" OUTPUT = "With trim() >" REVERSE(TRIM(REVERSE(TRIM(s1)))) "<"
- Remove all non-printing characters:
OUTPUT = "Original: >" s2 "<" s1 POS(0) SPAN(stripchars) = OUTPUT = "Leading: >" s1 "<" s2 ARB . s2 SPAN(stripchars) RPOS(0) OUTPUT = "Trailing: >" s2 "<" s2 POS(0) SPAN(stripchars) = OUTPUT = "Full trim: >" s2 "<"
END</lang>
- Output:
Original: > Hello, people of earth! < With trim() >Hello, people of earth!< Original: >� Hello, people of earth! �< Leading: >Hello, people of earth! < Trailing: >� Hello, people of earth!< Full trim: >Hello, people of earth!<
Standard ML
<lang sml>local
open Substring
in
val trimLeft = string o dropl Char.isSpace o full and trimRight = string o dropr Char.isSpace o full and trim = string o dropl Char.isSpace o dropr Char.isSpace o full
end</lang>
Stata
See strtrim in Stata help. Use the equivalent ustrtrim functions with Unicode strings.
<lang stata>s = " ars longa " "("+strtrim(s)+")"
(ars longa)
"("+strltrim(s)+")"
(ars longa )
"("+strrtrim(s)+")"
( ars longa)
"("+stritrim(s)+")"
( ars longa )</lang>
Tcl
Whitespace stripping is done with string trim and related commands:
<lang tcl>set str " hello world "
puts "original: >$str<"
puts "trimmed head: >[string trimleft $str]<"
puts "trimmed tail: >[string trimright $str]<"
puts "trimmed both: >[string trim $str]<"</lang>
- Output:
original: > hello world < trimmed head: >hello world < trimmed tail: > hello world< trimmed both: >hello world<
TI-83 BASIC
<lang ti-83b> PROGRAM:WHITESPC Input Str1 0→M Menu(" REMOVE ","TRAILIN WHTSPC",A,"LEADING WHTSPC",C,"BOTH",B)
Lbl B 1→M
Lbl A While sub(Str1,length(Str1)-1),1)=" " sub(Str1,1,length(Str1)-1)→Str1 End
If M=1 Then Goto C Else Goto F End
Lbl C While sub(str1,1,1)=" " sub(Str1,2,length(Str1)-1)→Str1 End
Lbl F Disp "'"+Str1+"'" </lang>
TorqueScript
Remove leading whitespace
$string = " yep "; $string = LTrim($string); echo($string);
Remove trailing whitespace
$string = " yep "; $string = RTrim($string); echo($string);
Remove leading and trailing white spaces
$string = " yep "; $string = trim($string); echo($string);
Output
"yep " " yep" "yep"
TUSCRIPT
<lang tuscript>$$ MODE TUSCRIPT str= " sentence w/whitespace before and after " trimmedtop=EXTRACT (str,":<|<> :"|,0) trimmedtail=EXTRACT (str,0,":<> >|:") trimmedboth=SQUEEZE(str) PRINT "string <|", str," >|" PRINT "trimmed on top <|",trimmedtop,">|" PRINT "trimmed on tail <|", trimmedtail,">|" PRINT "trimmed on both <|", trimmedboth,">|"</lang>
- Output:
string <| sentence w/whitespace before and after >| trimmed on top <|sentence w/whitespace before and after >| trimmed on tail <| sentence w/whitespace before and after>| trimmed on both <|sentence w/whitespace before and after>|
TXR
Pattern Matching Language Exercise
Here, no builtin functions are used, just text pattern matching logic. Two functions are written, conforming to the proper filter convention, and then employed as filters. <lang txr>@(define trim_left (in out)) @ (next :list in) @/[ \t]*/@out @(end) @(define trim_right (in out)) @ (local blanks middle) @ (next :list in) @ (cases) @ {blanks /[ \t]*/}@middle@/[\t ]+/ @ (bind out `@blanks@middle`) @ (or) @ out @ (end) @(end) @line_of_input @(output) trim-left: [@{line_of_input :filter (:fun trim_left)}] trim_right: [@{line_of_input :filter (:fun trim_right)}] trim_both: [@{line_of_input :filter ((:fun trim_left) (:fun trim_right))}] @(end)</lang>
- Output:
$ echo "" | txr trim.txr - trim-left: [] trim_right: [] trim_both: [] $ echo "a" | txr trim.txr - trim-left: [a] trim_right: [a] trim_both: [a] $ echo " a" | txr trim.txr - trim-left: [a] trim_right: [ a] trim_both: [a] $ echo " a " | txr trim.txr - trim-left: [a ] trim_right: [ a] trim_both: [a] $ echo " a b " | txr trim.txr - trim-left: [a b ] trim_right: [ a b] trim_both: [a b]
Using Lisp Primitives
Trimming whitespace from both ends is a builtin:
<lang sh>$ txr -p '(trim-str " a b ")' "a b"</lang>
An unnecessarily cryptic, though educational, left trim:
<lang sh>$ txr -p '[(do progn (del [@1 0..(match-regex @1 #/\s*/)]) @1) " a b "]' "a b "</lang>
Explanation: the basic structure is [function " a b "] where the function is an anonymous lambda generated using the do operator. The function is applied to the string " a b ".
The structure of the do is (do progn (blah @1) @1) where the forms make references to implicit argument @1, and so the generated lambda has one argument, essentially being: (lambda (arg) (blah arg) arg): do something with the argument (the string) and then return it.
What is done with the argument is this: (del [@1 0..(match-regex @1 #/\s+/)]). The match-regex function returns the number of characters at the front of the string which match the regex \s*: one or more spaces. The return value of this is used to express a range 0..length which is applied to the string. The syntax (del [str from..to]) deletes a range of characters in the string.
Lastly, a pedestrian right trim:
<lang txrlisp>(defun trim-right (str)
(for ()
((and (> (length str) 0) (chr-isspace [str -1])) str)
((del [str -1]))))
(format t "{~a}\n" (trim-right " a a ")) (format t "{~a}\n" (trim-right " ")) (format t "{~a}\n" (trim-right "a ")) (format t "{~a}\n" (trim-right ""))</lang>
Output:
{ a a}
{}
{a}
{}
Ursala
<lang Ursala>#import std
white = ==` !| not @iNC %sI trim_left = white-~r trim_right = white~-l trim_both = trim_left+ trim_right
- cast %sgUL
main = <.trim_left,trim_right,trim_both> ' string with spaces '</lang>
- The
whitepredicate tests an argument for whiteness by either comparing it to a literal space character or testing whether the singleton list containing it is of a string (%s) type. - The
-~postfix operator takes a predicate to a function that takes a string to a pair of strings whose concatenation is the original string and whose left side is the maximal prefix of the original string whose members satisfy the predicate. - The
rsuffix on the-~predicate extracts the right side of the pair of strings in the result. - The
~-operator is similar to the-~operator except that is concerned with the maximal suffix whose members satisfy the predicate. - The
lsuffix extracts the right side.
- Output:
< 'string with spaces ', ' string with spaces', 'string with spaces'>
Vala
Strip Leading White Space
<lang vala>string s = " word "; string s_chug = s.chug();</lang>
Strip Trailing White Space
<lang vala>string s = " word "; string s_chomp = s.chomp();</lang>
Strip Leading & Trailing White Space
<lang vala>string s = " word "; string s_strip = s.strip();</lang>
VBA
<lang vb>Public Sub test()
'LTrim trims leading spaces 'RTrim trims tailing spaces 'Trim trims both leading and tailing spaces s = " trim " Debug.Print """" & s & """" Debug.Print """" & LTrim(s) & """" Debug.Print """" & RTrim(s) & """" Debug.Print """" & WorksheetFunction.trim(s) & """" 'these functions do not remove tabs or newlines
End Sub</lang>
- Output:
" trim " "trim " " trim" "trim"
VBScript
<lang vb> Function LeftTrim(s) Set regex = New RegExp With regex .Pattern = "^\s*" If .Test(s) Then LeftTrim = .Replace(s,"") Else LeftTrim = s End If End With End Function
Function RightTrim(s) Set regex = New RegExp With regex .Pattern = "\s*$" If .Test(s) Then RightTrim = .Replace(s,"") Else RightTrim = s End If End With End Function
'testing the functions WScript.StdOut.WriteLine LeftTrim(" RosettaCode") WScript.StdOut.WriteLine RightTrim("RosettaCode ") WScript.StdOut.WriteLine LeftTrim(RightTrim(" RosettaCode ")) </lang>
- Output:
RosettaCode RosettaCode RosettaCode
Wren
In Wren 'whitespace' is defined as: space, tab, carriage return, and line feed characters. To trim off other non-printing characters such as form feed and vertical tab, you need to do a little more work. <lang ecmascript>var a = " \t\r\nString with leading whitespace removed" var b = "String with trailing whitespace removed \t\r\n" var c = " \t\r\nString with both leading and trailing whitespace removed \t\r\n" var d = " \t\r\n\f\vString with leading whitespace, form feed and verical tab characters removed" System.print("'%(a.trimStart())'") System.print("'%(b.trimEnd())'") System.print("'%(c.trim())'") System.print("'%(d.trimStart(" \t\r\n\f\v"))'") // similar overloads of trimEnd and trim exist</lang>
- Output:
'String with leading whitespace removed' 'String with trailing whitespace removed' 'String with both leading and trailing whitespace removed' 'String with leading whitespace, form feed and vertical tab characters removed'
XPL0
<lang XPL0>code ChOut=8, CrLf=9, Text=12; string 0; \use zero-terminated string convention
func StripLead(S0); \Strip leading whitespace (<=$20) from string char S0; char S1(80); \BEWARE: very temporary string space returned int I, J, C, Stripped; [I:= 0; J:= 0; Stripped:= false; repeat C:= S0(I); I:= I+1;
if Stripped ! C>$20 ! C=0 then
[S1(J):= C; J:= J+1; Stripped:= true];
until C=0; return S1; ];
func StripTrail(S0); \Strip trailing whitespace (<=$20) from string char S0; char S1(80); \BEWARE: very temporary string space returned int I, SI; [I:= 0; loop [if S0(I) <= $20 then
[SI:= I;
while S0(I) <= $20 do
[if S0(I) = 0 then [S1(SI):= 0; return S1];
S1(I):= S0(I); I:= I+1;
];
]
else [S1(I):= S0(I); I:= I+1];
];
];
char String; [String:= " Hello World "; Text(0, StripLead(String)); ChOut(0, ^!); CrLf(0); Text(0, StripTrail(String)); ChOut(0, ^!); CrLf(0); Text(0, StripTrail(StripLead(String))); ChOut(0, ^!); CrLf(0); ]</lang>
Output:
Hello World ! Hello World! Hello World!
Yabasic
<lang Yabasic>s$ = "\t test \n"
print "--",ltrim$(s$),"--" print "--",rtrim$(s$),"--" print "--",trim$(s$),"--"</lang>
zkl
Remove white space from both end of string: <lang zkl>"\t\n hoho\n\t\ ".strip() //-->"hoho"</lang> <lang zkl>fcn removeLeadingWS(s){ n:=0;
try{ while(s[n].isSpace()){ n+=1 } }catch{""}fallthrough{ s[n,*] }
} removeLeadingWS("\t\n hoho\n\t\ ") //-->"hoho\n\t " removeLeadingWS("") //-->""</lang> <lang zkl>fcn removeTrailingWS(s){ n:=-1;
try{ while(s[n].isSpace()){ n-=1 } s[0,n+1] }catch{""}
} removeTrailingWS("\t\n hoho\n\t\ ") //-->"\t\n hoho" removeTrailingWS("\t\n \n\t\ ") //-->""</lang>
Zoea
<lang Zoea> program: trim_left
input: ' abcd' output: 'abcd'
program: trim_right
input: 'abcd ' output: 'abcd'
program: trim
input: ' abcd ' output: 'abcd'
</lang>