Regular expressions
From Rosetta Code
You are encouraged to solve this task according to the task description, using any language you may know.
The goal of this task is
- to match a string against a regular expression
- to substitute part of a string using a regular expression
[edit] AppleScript
Library: Satimage.osax
try
find text ".*string$" in "I am a string" with regexp
on error message
return message
end try
try
change "original" into "modified" in "I am the original string" with regexp
on error message
return message
end try
[edit] ALGOL 68
The routines grep in strings and sub in string are not part of ALGOL 68's standard prelude.
Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386
INT match=0, no match=1, out of memory error=2, other error=3;
STRING str := "i am a string";
# Match: #
STRING m := "string$";
INT start, end;
IF grep in string(m, str, start, end) = match THEN printf(($"Ends with """g""""l$, str[start:end])) FI;
# Replace: #
IF sub in string(" a ", " another ",str) = match THEN printf(($gl$, str)) FI;
Output:
Ends with "string" i am another string
Standard ALGOL 68 does have an primordial form of pattern matching called a format. This is designed to extract values from input data. But it can also be used for outputting (and transputting) the original data.
Works with: ALGOL 68 version Standard - But declaring book as flex[]flex[]string
Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386
For example:FORMAT pattern = $ddd" "c("cats","dogs")$;
FILE file; STRING book; associate(file, book);
on value error(file, (REF FILE f)BOOL: stop);
on format error(file, (REF FILE f)BOOL: stop);
book := "100 dogs";
STRUCT(INT count, type) dalmatians;
getf(file, (pattern, dalmatians));
print(("Dalmatians: ", dalmatians, new line));
count OF dalmatians +:=1;
printf(($"Gives: "$, pattern, dalmatians, $l$))
Output:
Dalmatians: +100 +2 Gives 101 dogs
[edit] Argile
use std, regex
(: matching :)
if "some matchable string" =~ /^some" "+[a-z]*" "+string$/
echo string matches
else
echo string "doesn't" match
(: replacing :)
let t = strdup "some allocated string"
t =~ s/a/"4"/g
t =~ s/e/"3"/g
t =~ s/i/"1"/g
t =~ s/o/"0"/g
t =~ s/s/$/g
print t
free t
(: flushing regex allocations :)
uninit regex
check mem leak; use dbg (:optional:)
(note that it needs to be compiled with argrt library)
Output:
string matches $0m3 4ll0c4t3d $tr1ng
[edit] AutoHotkey
MsgBox % foundpos := RegExMatch("Hello World", "World$")
MsgBox % replaced := RegExReplace("Hello World", "World$", "yourself")
[edit] AWK
AWK supports regular expressions, which are typically marked up with slashes in front and back, and the "~" operator:
$ awk '{if($0~/[A-Z]/)print "uppercase detected"}'
abc
ABC
uppercase detected
As shorthand, a regular expression in the condition part fires if it matches an input line:
awk '/[A-Z]/{print "uppercase detected"}'
def
DeF
uppercase detected
For substitution, the first argument can be a regular expression, while the replacement string is constant (only that '&' in it receives the value of the match):
$ awk '{gsub(/[A-Z]/,"*");print}'
abCDefG
ab**ef*
$ awk '{gsub(/[A-Z]/,"(&)");print}'
abCDefGH
ab(C)(D)ef(G)(H)
This variant matches one or more uppercase letters in one round:
$ awk '{gsub(/[A-Z]+/,"(&)");print}'
abCDefGH
ab(CD)ef(GH)
[edit] C
Works with: POSIX
As far as I can see, POSIX defined function for regex matching, but nothing for substitution. So we must do all the hard work by hand. The complex-appearing code could be turned into a function.
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <regex.h>
#include <string.h>
int main()
{
regex_t preg;
regmatch_t substmatch[1];
const char *tp = "string$";
const char *t1 = "this is a matching string";
const char *t2 = "this is not a matching string!";
const char *ss = "istyfied";
regcomp(&preg, "string$", REG_EXTENDED);
printf("'%s' %smatched with '%s'\n", t1,
(regexec(&preg, t1, 0, NULL, 0)==0) ? "" : "did not ", tp);
printf("'%s' %smatched with '%s'\n", t2,
(regexec(&preg, t2, 0, NULL, 0)==0) ? "" : "did not ", tp);
regfree(&preg);
/* change "a[a-z]+" into "istifyed"?*/
regcomp(&preg, "a[a-z]+", REG_EXTENDED);
if ( regexec(&preg, t1, 1, substmatch, 0) == 0 )
{
//fprintf(stderr, "%d, %d\n", substmatch[0].rm_so, substmatch[0].rm_eo);
char *ns = malloc(substmatch[0].rm_so + 1 + strlen(ss) +
(strlen(t1) - substmatch[0].rm_eo) + 2);
memcpy(ns, t1, substmatch[0].rm_so+1);
memcpy(&ns[substmatch[0].rm_so], ss, strlen(ss));
memcpy(&ns[substmatch[0].rm_so+strlen(ss)], &t1[substmatch[0].rm_eo],
strlen(&t1[substmatch[0].rm_eo]));
ns[ substmatch[0].rm_so + strlen(ss) +
strlen(&t1[substmatch[0].rm_eo]) ] = 0;
printf("mod string: '%s'\n", ns);
free(ns);
} else {
printf("the string '%s' is the same: no matching!\n", t1);
}
regfree(&preg);
return 0;
}
[edit] C++
Works with: g++ version 4.0.2
Library: Boost
#include <iostream>
#include <string>
#include <iterator>
#include <boost/regex.hpp>
int main()
{
boost::regex re(".* string$");
std::string s = "Hi, I am a string";
// match the complete string
if (boost::regex_match(s, re))
std::cout << "The string matches.\n";
else
std::cout << "Oops - not found?\n";
// match a substring
boost::regex re2(" a.*a");
boost::smatch match;
if (boost::regex_search(s, match, re2))
{
std::cout << "Matched " << match.length()
<< " characters starting at " << match.position() << ".\n";
std::cout << "Matched character sequence: \""
<< match.str() << "\"\n";
}
else
{
std::cout << "Oops - not found?\n";
}
// replace a substring
std::string dest_string;
boost::regex_replace(std::back_inserter(dest_string),
s.begin(), s.end(),
re2,
"'m now a changed");
std::cout << dest_string << std::endl;
}
[edit] C#
using System;
using System.Text.RegularExpressions;
class Program {
static void Main(string[] args) {
string str = "I am a string";
if (new Regex("string$").IsMatch(str)) {
Console.WriteLine("Ends with string.");
}
str = new Regex(" a ").Replace(str, " another ");
Console.WriteLine(str);
}
}
[edit] Clojure
(let [s "I am a string"]
;; match
(when (re-find #"string$" s)
(println "Ends with 'string'."))
(when-not (re-find #"^You" s)
(println "Does not start with 'You'."))
;; substitute (using Java)
(println (.replaceAll s " a " " another "))
)
[edit] Common Lisp
Translation of: Perl
Uses CL-PPCRE - Portable Perl-compatible regular expressions for Common Lisp.
(let ((string "I am a string"))
(when (cl-ppcre:scan "string$" string)
(write-line "Ends with string"))
(unless (cl-ppcre:scan "^You" string )
(write-line "Does not start with 'You'")))
Substitute
(let* ((string "I am a string")
(string (cl-ppcre:regex-replace " a " string " another ")))
(write-line string))
Test and Substitute
(let ((string "I am a string"))
(multiple-value-bind (string matchp)
(cl-ppcre:regex-replace "\\bam\\b" string "was")
(when matchp
(write-line "I was able to find and replace 'am' with 'was'."))))
[edit] D
import std.stdio, std.regexp;
void main() {
string s = "I am a string";
// Test:
if (search(s, r"string$"))
writefln("Ends with 'string'");
// Test, storing the regular expression:
auto re1 = RegExp(r"string$");
if (re1.search(s).test)
writefln("Ends with 'string'");
// Substitute:
writefln(sub(s, " a ", " another "));
// Substitute, storing the regular expression:
auto re2 = RegExp(" a ");
writefln(re2.replace(s, " another "));
}
Note that in std.string there are string functions to perform those string operations in a faster way.
[edit] Erlang
match() ->
String = "This is a string",
case re:run(String, "string$") of
{match,_} -> io:format("Ends with 'string'~n");
_ -> ok
end.
substitute() ->
String = "This is a string",
NewString = re:replace(String, " a ", " another ", [{return, list}]),
io:format("~s~n",[NewString]).
[edit] Forth
Library: Forth Foundation Library Test/Match
include ffl/rgx.fs
\ Create a regular expression variable 'exp' in the dictionary
rgx-create exp
\ Compile an expression
s" Hello (World)" exp rgx-compile [IF]
.( Regular expression successful compiled.) cr
[THEN]
\ (Case sensitive) match a string with the expression
s" Hello World" exp rgx-cmatch? [IF]
.( String matches with the expression.) cr
[ELSE]
.( No match.) cr
[THEN]
[edit] Go
package main
import "fmt"
import "regexp"
func main() {
str := "I am the original string"
// Test
matched, _ := regexp.MatchString(".*string$", str)
if matched { fmt.Println("ends with 'string'") }
// Substitute
pattern := regexp.MustCompile("original")
result := pattern.replaceAllString(str, "modified")
fmt.Println(result)
}
[edit] Haskell
Test
import Text.Regex
str = "I am a string"
case matchRegex (mkRegex ".*string$") str of
Just _ -> putStrLn $ "ends with 'string'"
Nothing -> return ()
Substitute
import Text.Regex
orig = "I am the original string"
result = subRegex (mkRegex "original") orig "modified"
putStrLn $ result
[edit] HicEst
CHARACTER string*100/ "The quick brown fox jumps over the lazy dog" /
REAL, PARAMETER :: Regex=128, Count=256
characters_a_m = INDEX(string, "[a-m]", Regex+Count) ! counts 16
vocals_changed = EDIT(Text=string, Option=Regex, Right="[aeiou]", RePLaceby='**', DO=LEN(string) ) ! changes 11
WRITE(ClipBoard) string ! Th** q****ck br**wn f**x j**mps **v**r th** l**zy d**g
[edit] Icon and Unicon
The Library: Icon Programming Library provides regexp. Regex includes procedures to provide access to regular expressions within native string scanning and matching expressions. 'ReFind' and 'ReMatch' respectively generate the sequence of beginning and ending positions matched by a regular expression. Additionally, there is a regular expression pattern compiler 'RePat' and other supporting functions and variables.
[edit] Icon
procedure main()Sample output:
s := "A simple string"
p := "string$" # regular expression
s ? write(image(s),if ReFind(p) then " matches " else " doesn't match ",image(p))
s[j := ReFind(p,s):ReMatch(p,s,j)] := "replacement"
write(image(s))
end
link regexp # link to IPL regexp
"A simple string" matches "string$" "A simple replacement"
[edit] Unicon
The Icon solution works in Unicon.
[edit] J
J's regex support is built on top of PCRE.
load'regex' NB. Load regex library
str =: 'I am a string' NB. String used in examples.
Matching:
'.*string$' rxeq str NB. 1 is true, 0 is false
1
Substitution:
('am';'am still') rxrplc strNote: use
I am still a string
open'regex' to read the source code for the library. The comments list 6 main definitions and a dozen utility definitions.
[edit] Java
Works with: Java version 1.5+ Test
String str = "I am a string";
if (str.matches(".*string")) { // note: matches() tests if the entire string is a match
System.out.println("ends with 'string'");
}
Substitute
String orig = "I am the original string";
String result = orig.replaceAll("original", "modified");
// result is now "I am the modified string"
[edit] JavaScript
Test/Match
var subject = "Hello world!";
// Two different ways to create the RegExp object
// Both examples use the exact same pattern... matching "hello"
var re_PatternToMatch = /Hello (World)/i; // creates a RegExp literal with case-insensitivity
var re_PatternToMatch2 = new RegExp("Hello (World)", "i");
// Test for a match - return a bool
var isMatch = re_PatternToMatch.test(subject);
// Get the match details
// Returns an array with the match's details
// matches[0] == "Hello world"
// matches[1] == "world"
var matches = re_PatternToMatch2.exec(subject);
Substitute
var subject = "Hello world!";
// Perform a string replacement
// newSubject == "Replaced!"
var newSubject = subject.replace(re_PatternToMatch, "Replaced");
[edit] M4
regexp(`GNUs not Unix', `\<[a-z]\w+')
regexp(`GNUs not Unix', `\<[a-z]\(\w+\)', `a \& b \1 c')
Output:
5 a not b ot c
[edit] MIRC Scripting Language
alias regular_expressions {
var %string = This is a string
var %re = string$
if ($regex(%string,%re) > 0) {
echo -a Ends with string.
}
%re = \ba\b
if ($regsub(%string,%re,another,%string) > 0) {
echo -a Result 1: %string
}
%re = \b(another)\b
echo -a Result 2: $regsubex(%string,%re,yet \1)
}
Output:
Ends with string. Result 1: This is another string Result 2: This is yet another string
[edit] MUMPS
MUMPS doesn't have a replacement functionality when using the pattern matching operator, ?. We can mimic it with $PIECE, but $PIECE doesn't work with regular expressions as an operand.
REGEXPUsage:
NEW HI,W,PATTERN,BOOLEAN
SET HI="Hello, world!",W="world"
SET PATTERN=".E1"""_W_""".E"
SET BOOLEAN=HI?@PATTERN
WRITE "Source string - '"_HI_"'",!
WRITE "Partial string - '"_W_"'",!
WRITE "Pattern string created is - '"_PATTERN_"'",!
WRITE "Match? ",$SELECT(BOOLEAN:"YES",'BOOLEAN:"No"),!
;
SET BOOLEAN=$FIND(HI,W)
IF BOOLEAN>0 WRITE $PIECE(HI,W,1)_"string"_$PIECE(HI,W,2)
QUIT
USER>D REGEXP^ROSETTA Source string - 'Hello, world!' Partial string - 'world' Pattern string created is - '.E1"world".E' Match? YES Hello, string!
[edit] Objective-C
Test Works with: Mac OS X version 10.4+
NSString *str = @"I am a string";
NSString *regex = @".*string$";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
if ([pred evaluateWithObject:str]) {
NSLog(@"ends with 'string'");
}
Unfortunately this method cannot find the location of the match or do substitution.
[edit] OCaml
[edit] With the standard library
Test
#load "str.cma";;
let str = "I am a string";;
try
ignore(Str.search_forward (Str.regexp ".*string$") str 0);
print_endline "ends with 'string'"
with Not_found -> ()
;;
Substitute
#load "str.cma";;
let orig = "I am the original string";;
let result = Str.global_replace (Str.regexp "original") "modified" orig;;
(* result is now "I am the modified string" *)
[edit] Using Pcre
Library: ocaml-pcre
let matched pat str =
try ignore(Pcre.exec ~pat str); (true)
with Not_found -> (false)
;;
let () =
Printf.printf "matched = %b\n" (matched "string$" "I am a string");
Printf.printf "Substitute: %s\n"
(Pcre.replace ~pat:"original" ~templ:"modified" "I am the original string")
;;
[edit] Oz
declare
[Regex] = {Module.link ['x-oz://contrib/regex']}
String = "This is a string"
in
if {Regex.search "string$" String} \= false then
{System.showInfo "Ends with string."}
end
{System.showInfo {Regex.replace String " a " fun {$ _ _} " another " end}}
[edit] Perl
Works with: Perl version 5.8.8 Test
$string = "I am a string";
if ($string =~ /string$/) {
print "Ends with 'string'\n";
}
if ($string !~ /^You/) {
print "Does not start with 'You'\n";
}
Substitute
$string = "I am a string";
$string =~ s/ a / another /; # makes "I am a string" into "I am another string"
print $string;
Test and Substitute
$string = "I am a string";
if ($string =~ s/\bam\b/was/) { # \b is a word border
print "I was able to find and replace 'am' with 'was'\n";
}
Options
# add the following just after the last / for additional control
# g = globally (match as many as possible)
# i = case-insensitive
# s = treat all of $string as a single line (in case you have line breaks in the content)
# m = multi-line (the expression is run on each line individually)
$string =~ s/i/u/ig; # would change "I am a string" into "u am a strung"
[edit] PHP
Works with: PHP version 5.2.0
$string = 'I am a string';
Test
if (preg_match('/string$/', $string))
{
echo "Ends with 'string'\n";
}
Replace
$string = preg_replace('/\ba\b/', 'another', $string);
echo "Found 'a' and replace it with 'another', resulting in this string: $string\n";
[edit] PicoLisp
[edit] Calling the C library
PicoLisp doesn't have built-in regex functionality. It is easy to call the native C library.
(let (Pat "a[0-9]z" String "a7z")
(use Preg
(native "@" "regcomp" 'I '(Preg (64 B . 64)) Pat 1) # Compile regex
(when (=0 (native "@" "regexec" 'I (cons NIL (64) Preg) String 0 0 0))
(prinl "String \"" String "\" matches regex \"" Pat "\"") ) ) )
Output:
String "a7z" matches pattern "a[0-9]z"
[edit] Using Pattern Matching
Regular expressions are static and inflexible. Another possibility is dynamic pattern matching, where arbitrary conditions can be programmed.
(let String "The number <7> is incremented"
(use (@A @N @Z)
(and
(match '(@A "<" @N ">" @Z) (chop String))
(format @N)
(prinl @A "<" (inc @) ">" @Z) ) ) )
Output:
The number <8> is incremented
[edit] PowerShell
"I am a string" -match '\bstr' # true
"I am a string" -replace 'a\b','no' # I am no string
By default both the -match and -replace operators are case-insensitive. They can be made case-sensitive by using the -cmatch and -creplace operators.
[edit] PureBasic
String$ = "<tag>some text consisting of Roman letters spaces and numbers like 12</tag>"
regex$ = "<([a-z]*)>[a-z,A-Z,0-9, ]*</\1>"
regex_replace$ = "letters[a-z,A-Z,0-9, ]*numbers[a-z,A-Z,0-9, ]*"
If CreateRegularExpression(1, regex$) And CreateRegularExpression(2, regex_replace$)
If MatchRegularExpression(1, String$)
Debug "Tags correct, and only alphanummeric or space characters between them"
EndIf
Debug ReplaceRegularExpression(2, String$, "char stuff")
EndIf
[edit] Python
import re
string = "This is a string"
if re.search('string$',string):
print "Ends with string."
string = re.sub(" a "," another ",string)
print string
[edit] R
First, define some strings.
pattern <- "string"
text1 <- "this is a matching string"
text2 <- "this does not match"
Matching with grep. The indices of the texts containing matches are returned.
grep(pattern, c(text1, text2)) # 1
Matching with regexpr. The positions of the starts of the matches are returned, along with the lengths of the matches.
regexpr(pattern, c(text1, text2))
[1] 20 -1 attr(,"match.length") [1] 6 -1
Replacement
gsub(pattern, "pair of socks", c(text1, text2))
[1] "this is a matching pair of socks" "this does not match"
[edit] Raven
'i am a string' as str
Match:
str m/string$/
if "Ends with 'string'\n" print
Replace:
str r/ a / another / print
[edit] REBOL
rebol [
Title: "Regular Expression Matching"
Author: oofoe
Date: 2009-12-06
URL: http://rosettacode.org/wiki/Regular_expression_matching
]
string: "This is a string."
; REBOL doesn't use a conventional Perl-compatible regular expression
; syntax. Instead, it uses a variant Parsing Expression Grammar with
; the 'parse' function. It's also not limited to just strings. You can
; define complex grammars that actually parse and execute program
; files.
; Here, I provide a rule to 'parse' that specifies searching through
; the string until "string." is found, then the end of the string. If
; the subject string satisfies the rule, the expression will be true.
if parse string [thru "string." end] [
print "Subject ends with 'string.'"]
; For replacement, I take advantage of the ability to call arbitrary
; code when a pattern is matched -- everything in the parens will be
; executed when 'to " a "' is satisfied. This marks the current string
; location, then removes the offending word and inserts the replacement.
parse string [
to " a " ; Jump to target.
mark: (
remove/part mark 3 ; Remove target.
mark: insert mark " another " ; Insert replacement.
)
:mark ; Pick up where I left off.
]
print [crlf "Parse replacement:" string]
; For what it's worth, the above operation is more conveniently done
; with the 'replace' function:
replace string " another " " a " ; Change string back.
print [crlf "Replacement:" string]
Output:
Subject ends with 'string.' Parse replacement: This is another string. Replacement: This is a string.
[edit] Ruby
Test
string="I am a string"
puts "Ends with 'string'" if string[/string$/]
puts "Does not start with 'You'" if !string[/^You/]
Substitute
puts string.gsub(/ a /,' another ')
#or
string[/ a /]='another'
puts string
Substitute using block
puts(string.gsub(/\bam\b/) do |match|
puts "I found #{match}"
#place "was" instead of the match
"was"
end)
[edit] Sather
Sather understands POSIX regular expressions.
class MAIN is
-- we need to implement the substitution
regex_subst(re:REGEXP, s, sb:STR):STR is
from, to:INT;
re.match(s, out from, out to);
if from = -1 then return s; end;
return s.head(from) + sb + s.tail(s.size - to);
end;
main is
s ::= "I am a string";
re ::= REGEXP::regexp("string$", true);
if re.match(s) then
#OUT + "'" + s + "'" + " ends with 'string'\n";
end;
if ~REGEXP::regexp("^You", false).match(s) then
#OUT + "'" + s + "'" + " does not begin with 'You'\n";
end;
#OUT + regex_subst(re, s, "integer") + "\n";
#OUT + regex_subst(REGEXP::regexp("am +a +st", true), s, "get the ") + "\n";
end;
end;
[edit] Scala
Define
val Bottles1 = "(\\d+) bottles of beer".r // syntactic sugar
val Bottles2 = """(\d+) bottles of beer""".r // using triple-quotes to preserve backslashes
val Bottles3 = new scala.util.matching.Regex("(\\d+) bottles of beer") // standard
val Bottles4 = new scala.util.matching.Regex("""(\d+) bottles of beer""", "bottles") // with named groups
Search and replace with string methods:
"99 bottles of beer" matches "(\\d+) bottles of beer" // the full string must match
"99 bottles of beer" replace ("99", "98") // Single replacement
"99 bottles of beer" replaceAll ("b", "B") // Multiple replacement
Search with regex methods:
"\\d+".r findFirstIn "99 bottles of beer" // returns first partial match, or None
"\\w+".r findAllIn "99 bottles of beer" // returns all partial matches as an iterator
"\\s+".r findPrefixOf "99 bottles of beer" // returns a matching prefix, or None
Bottles4 findFirstMatchIn "99 bottles of beer" // returns a "Match" object, or None
Bottles4 findPrefixMatchOf "99 bottles of beer" // same thing, for prefixes
val bottles = (Bottles4 findFirstMatchIn "99 bottles of beer").get.group("bottles") // Getting a group by name
Using pattern matching with regex:
val Some(bottles) = Bottles4 findPrefixOf "99 bottles of beer" // throws an exception if the matching fails; full string must match
for {
line <- """|99 bottles of beer on the wall
|99 bottles of beer
|Take one down, pass it around
|98 bottles of beer on the wall""".stripMargin.lines
} line match {
case Bottles1(bottles) => println("There are still "+bottles+" bottles.") // full string must match, so this will match only once
case _ =>
}
for {
matched <- "(\\w+)".r findAllIn "99 bottles of beer" matchData // matchData converts to an Iterator of Match
} println("Matched from "+matched.start+" to "+matched.end)
Replacing with regex:
Bottles2 replaceFirstIn ("99 bottles of beer", "98 bottles of beer")
Bottles3 replaceAllIn ("99 bottles of beer", "98 bottles of beer")
[edit] Slate
This library is still in its early stages. There isn't currently a feature to replace a substring.
'http://slatelanguage.org/test/page?query' =~ '^(([^:/?#]+)\\:)?(//([^/?#]*))?([^?#]*)(\\?([^#]*))?(#(.*))?'.
" ==> {'http:'. 'http'. '//slatelanguage.org'. 'slatelanguage.org'. '/test/page'. '?query'. 'query'. Nil} "
[edit] Smalltalk
|re s s1|
re := Regex fromString: '[a-z]+ing'.
s := 'this is a matching string'.
s1 := 'this does not match'.
(s =~ re)
ifMatched: [ :b |
b match displayNl
].
(s1 =~ re)
ifMatched: [ :b |
'Strangely matched!' displayNl
]
ifNotMatched: [
'no match!' displayNl
].
(s replacingRegex: re with: 'modified') displayNl.
[edit] Tcl
Test using regexp:
set theString "I am a string"
if {[regexp -- {string$} $theString]} {
puts "Ends with 'string'"
}
if {![regexp -- {^You} $theString]} {
puts "Does not start with 'You'"
}
Extract substring using regexp
set theString "This string has >123< a number in it"
if {[regexp -- {>(\d+)<} $theString -> number]} {
puts "Contains the number $number"
}
Substitute using regsub
set theString = "I am a string"
puts [regsub -- { +a +} $theString { another }]
[edit] Toka
Toka's regular expression library allows for matching, but does not yet provide for replacing elements within strings.
#! Include the regex library
needs regex
#! The two test strings
" This is a string" is-data test.1
" Another string" is-data test.2
#! Create a new regex named 'expression' which tries
#! to match strings beginning with 'This'.
" ^This" regex: expression
#! An array to store the results of the match
#! (Element 0 = starting offset, Element 1 = ending offset of match)
2 cells is-array match
#! Try both test strings against the expression.
#! try-regex will return a flag. -1 is TRUE, 0 is FALSE
expression test.1 2 match try-regex .
expression test.2 2 match try-regex .
[edit] Vedit macro language
Vedit can perform searches and matching with either regular expressions, pattern matching codes or plain text. These examples use regular expressions.
Match text at cursor location:
if (Match(".* string$", REGEXP)==0) {
Statline_Message("This line ends with 'string'")
}
Search for a pattern:
if (Search("string$", REGEXP+NOERR)) {
Statline_Message("'string' at and of line found")
}
Replace:
Replace(" a ", " another ", REGEXP+NOERR)

