Remove non-letters from a string

From CodeCodex

Revision as of 08:15, 11 December 2009 by 164.67.235.128 (Talk)

Related content:

Implementations

Java

This code removes common symbols and numbers from a string, returning letters only. (Note, not all symbols are included.)

static String lettersOnly(String s) {
   return s.replaceAll("[^a-zA-Z]","");
}

C

if buff's content is: "15+41-2Hel54lo **1212 Wor2ld! Ho5w Are 6996 Yo7u?" then the content of buff_02 will be: "HelloWorldHowAreYou" <HIGHLIGHTSYNTAX language="c">#include <string.h>

while (i != strlen (buff)) { if ((buff[i] >= 65) && (buff[i] <= 90) || (buff[i] >= 97) && (buff[i] <= 122)) { buff_02[j] = buff[i]; i++; j++; } else { i++; } } </HIGHLIGHTSYNTAX>

JavaScript

<HIGHLIGHTSYNTAX language="javascript"> var s = "how19 a*re 254y**ou?";

document.write(s.replace(/[^A-Za-z]/g, "")); </HIGHLIGHTSYNTAX>

OCaml

# let remove_nonalpha = Str.global_replace (Str.regexp "[^a-zA-Z]+") "";;
val remove_nonalpha : string -> string = <fun>

For example:

# remove_nonalpha "133t H4x0r";;
- : string = "tHxr"

Perl

<HIGHLIGHTSYNTAX language="perl">

s{[\W\d_]}{}g; # remove all non-word characters and digits and underscores

</HIGHLIGHTSYNTAX>

PHP

<HIGHLIGHTSYNTAX language="php3"> $result = preg_replace('/[^A-Za-z]/', , $string); </HIGHLIGHTSYNTAX>

Python

<HIGHLIGHTSYNTAX language="python"> s = "hello world! how are you? 0"

  1. Short version

print filter(lambda c: c.isalpha(), s)

  1. Faster version for long ASCII strings:

id_tab = "".join(map(chr, xrange(256))) tostrip = "".join(c for c in id_tab if c.isalpha()) print s.translate(id_tab, tostrip)

  1. Using regular expressions

print re.sub("[^A-Za-z]", "", s) </HIGHLIGHTSYNTAX>

Tcl

proc remove_non_ascii_letters s {regsub -all {[^a-zA-Z]} $s ""}
remove_non_ascii_letters "hello world! how are you? 0é" ;# -> helloworldhowareyou

Visual Basic

Public Function ReturnAlpha(ByVar sString As String) As String
Dim i As Integer
For i = 1 To Len(sString)
    If Mid(sString, i, 1) Like "[A-Za-z]" Then
        ReturnAlpha = ReturnAlpha + Mid(sString, i, 1)
    End If
Next i
End Function

WinBatch

; Remove non-letters from a string, assuming space as non-letter character.

strString = "15+41-2Hel54lo **1212 Wor2ld! Ho5w Are 6996 Yo7u?"

; Example 1
strClean1 = StrClean (strString, "0123456789+-*/!?.,;:~@ ", "", @TRUE, 1) 
; strClean1 = "HelloWorldHowAreYou"

; Example 2
strClean2 = StrClean (strString, "abcdefghijklmnopqrstuvwxyz", "", @FALSE, 2) 
; strClean2 = "HelloWorldHowAreYou"

; Example 3
objRegExp = ObjectCreate ("VBScript.RegExp")
objRegExp.IgnoreCase = @TRUE
objRegExp.MultiLine = @FALSE
objRegExp.Global = @TRUE
objRegExp.Pattern = "[^a-z]"
strClean3 = objRegExp.Replace(strString, "") 
objRegExp = 0
; strClean3 = "HelloWorldHowAreYou"

Exit
; This code example was written by Detlev Dalitz.

Zsh

s="Hello, World! How are you? 1... 2... 3..."
print "${s//[^a-zA-Z]/}"