Strip control codes and extended characters from a string

Strip control codes and extended characters from a string is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

The task is to strip control codes and extended characters from a string. The solution should demonstrate how to achieve each of the following results:

• a string with control codes stripped (but extended characters not stripped)
• a string with control codes and extended characters stripped

In ASCII, the control codes have decimal codes 0 through to 31 and 127 and the extended characters have decimal codes greater than 127. On an ASCII based system, if the control codes and the extended characters are stripped, the resultant string would have all of its characters within the range of 32 to 126 decimal on the ascii table.

On a non-ASCII based system, we consider characters that do not have a corresponding glyph on the ASCII table (within the ASCII range of 32 to 126 decimal) to be an extended character for the purpose of this task.

J

Solution: <lang j>stripControlCodes=: -.&(DEL,32{.a.) stripControlExtCodes=: ([ -. -.)&(32}.127{.a.)</lang> Usage: <lang j> mystring=: a. {~ ?~256 NB. ascii chars 0-255 in random order

  #mystring                       NB. length of string

256

  #stripControlCodes mystring     NB. length of string without control codes

223

  #stripControlExtCodes mystring  NB. length of string without control codes or extended chars

95

  #myunicodestring=: u: ?~1000     NB. unicode characters 0-999 in random order

1000

  #stripControlCodes myunicodestring

967

  #stripControlExtCodes myunicodestring

95

  stripControlExtCodes myunicodestring

k}w:]U3xEh9"GZdr/#^B.Sn%\uFOo[(`t2-J6*IA=Vf&N;lQ8,${XLz5?D0~s)'Y7Kq|ip4<WRCaM!b@cgv_T +mH>1ejPy</lang>

PicoLisp

Control characters in strings are written with a hat (^) in PicoLisp. ^? is the DEL character. <lang PicoLisp>(de stripCtrl (Str)

  (pack
     (filter
        '((C)
           (nor (= "^?" C) (> " " C "^A")) )
        (chop Str) ) ) )

(de stripCtrlExt (Str)

  (pack
     (filter
        '((C) (> "^?" C "^_"))
        (chop Str) ) ) )</lang>

Test:

: (char "^?")
-> 127

: (char "^_")
-> 31

: (stripCtrl "^I^M a b c^? d äöüß")
-> " a b c d äöüß"

: (stripCtrlExt "^I^M a b c^? d äöüß")
-> " a b c d "

PureBasic

<lang PureBasic>Procedure.s stripControlCodes(source.s)

 Protected i, *ptrChar.Character, length = Len(source), result.s
 *ptrChar = @source
 For i = 1 To length
   If *ptrChar\c > 31 
     result + Chr(*ptrChar\c)
   EndIf
   *ptrChar + SizeOf(Character)
 Next
 ProcedureReturn result 

EndProcedure

Procedure.s stripControlExtCodes(source.s)

 Protected i, *ptrChar.Character, length = Len(source), result.s
 *ptrChar = @source
 For i = 1 To length
   If *ptrChar\c > 31 And *ptrChar\c < 128
     result + Chr(*ptrChar\c)
   EndIf
   *ptrChar + SizeOf(Character)
 Next
 ProcedureReturn result 

EndProcedure

If OpenConsole()

 ;create sample string
 Define i, s.s
 For i = 1 To 80
   s + Chr(Random(254) + 1) ;include character values from 1 to 255
 Next 

 PrintN(stripControlCodes(s))    ;string without control codes 
 PrintN("---------")
 PrintN(stripControlExtCodes(s)) ;string without control codes or extended chars
 
 Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
 CloseConsole()

EndIf</lang> Sample output:

»╫=┐C─≡G(═ç╤â√╝÷╔¬ÿ▌x  è4∞|)ï└⌐ƒ9²òτ┌ºáj)▓<~-vPÿφQ╨ù¿╖îFh"[ü╗dÉ₧q#óé├p╫■
---------
=CG(x 4|)9j)<~-vPQFh"[dq#p