Regular expressions
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
-
- match a string against a regular expression
- substitute part of a string using a regular expression
11l
V string = ‘This is a string’
I re:‘string$’.search(string)
print(‘Ends with string.’)
string = string.replace(re:‘ a ’, ‘ another ’)
print(string)- Output:
Ends with string. This is another string
8th
"haystack" /a./ r:match . cr
"haystack" /a./ "blah" s:replace! . cr
- Output:
1 hblahstblahk
ABAP
DATA: text TYPE string VALUE 'This is a Test'.
FIND FIRST OCCURRENCE OF REGEX 'is' IN text.
IF sy-subrc = 0.
cl_demo_output=>write( 'Regex matched' ).
ENDIF.
REPLACE ALL OCCURRENCES OF REGEX '[t|T]est' IN text WITH 'Regex'.
cl_demo_output=>write( text ).
cl_demo_output=>display( ).
Output:
Regex matched This is a Regex
Ada
There is no Regular Expression library in the Ada Standard, so I am using one of the libraries provided by gnat/gcc.
with Ada.Text_IO; with Gnat.Regpat; use Ada.Text_IO;
procedure Regex is
package Pat renames Gnat.Regpat;
procedure Search_For_Pattern(Compiled_Expression: Pat.Pattern_Matcher;
Search_In: String;
First, Last: out Positive;
Found: out Boolean) is
Result: Pat.Match_Array (0 .. 1);
begin
Pat.Match(Compiled_Expression, Search_In, Result);
Found := not Pat."="(Result(1), Pat.No_Match);
if Found then
First := Result(1).First;
Last := Result(1).Last;
end if;
end Search_For_Pattern;
Word_Pattern: constant String := "([a-zA-Z]+)";
Str: String:= "I love PATTERN matching!";
Current_First: Positive := Str'First;
First, Last: Positive;
Found: Boolean;
begin
-- first, find all the words in Str
loop
Search_For_Pattern(Pat.Compile(Word_Pattern),
Str(Current_First .. Str'Last),
First, Last, Found);
exit when not Found;
Put_Line("<" & Str(First .. Last) & ">");
Current_First := Last+1;
end loop;
-- second, replace "PATTERN" in Str by "pattern"
Search_For_Pattern(Pat.Compile("(PATTERN)"), Str, First, Last, Found);
Str := Str(Str'First .. First-1) & "pattern" & Str(Last+1 .. Str'Last);
Put_Line(Str);
end Regex;
- Output:
<I> <love> <PATTERN> <matching> I love pattern matching!
ALGOL 68
The routines grep in strings and sub in string are not part of ALGOL 68's standard prelude.
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.
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
Amazing Hopper
task 1: match a string against a regular expression (Hopper use POSIX):
#include <hopper.h>
main:
expReg="[A-Z]{1,2}[0-9][0-9A-Z]? +[0-9][A-Z]{2}"
flag compile = REG_EXTENDED
flag match=0
número de matches=10, T1=0
{flag compile,expReg} reg compile(T1) // compile regular expression, pointed whit T1
{flag match,número de matches,T1,"We are at SN12 7NY for this course"},reg match, // execute
println
reg free(T1) // free pointer to regular expression compiled.
exit(0)- Output:
11 18 SN12 7NY
Task 2: Hopper does not substitute using regular expressions, but using proper functions.
#include <hopper.h>
main:
expReg="[A-Z]{1,2}[0-9][0-9A-Z]? +[0-9][A-Z]{2}"
cadena = "We are at SN12 7NY for this course"
flag compile = REG_EXTENDED
flag match=0
número de matches=10, T1=0
{flag compile,expReg} reg compile(T1) // compile regular expression, pointed whit T1
{flag match,número de matches,T1,cadena},reg match, // execute
matches=0,mov(matches)
reg free(T1) // free pointer to regular expression compiled.
From=0, To=0, toSearch=""
[1,1]get(matches), mov(From)
[1,2]get(matches), mov(To)
[1,3]get(matches), mov(toSearch)
// substitute with "transform":
{"another thing",toSearch,cadena}transform, println
// substitute with "delete"/"insert":
{To}minus(From),plus(1), {From, cadena} delete, mov(cadena)
{From,"another thing",cadena}insert , println
exit(0)- Output:
We are at another thing for this course We are at another thing for this course
AppleScript
try
find text ".*string$" in "I am a string" with regexp
on error message
return message
end try
try
change "original" into "modified" in "I am the original string" with regexp
on error message
return message
end try
As from macOS 10.14 Mojave, third-party scripting additions (OSAXen) such as the Satimage OSAX are essentially unusable. (One of Apple's increasingly tight security measures.) They are allowed under very strict conditions as part of an application's own resources and Late Night Software, the developer of Script Debugger, has released a SatimageOSAX application as a stop-gap measure to allow existing Satimage-dependent scripts to be used with minimal editing until they're rewritten to use other commands.
The alternatives at the moment are to use one of the text-editing languages available through the do shell script command (AppleScript's own StandardAdditions OSAX does still work) or to use AppleScriptObjectiveC. The scripts below assume it's known that the strings will consist of just one line.
do shell script:
-- Get the run of non-white-space at the end, if any.
try
set output to (do shell script "echo 'I am a string' | egrep -o '\\S+$'")
on error message
set output to "No match"
end try
-- Replace the first instance of "orig…" with "modified".
set moreOutput to(do shell script "echo 'I am the original string' | sed 's/orig[a-z]*/modified/'")
return output & linefeed & moreOutput
ASObjC uses ICU regex:
use AppleScript version "2.4" -- OS X 10.10 (Yosemite) or later
use framework "Foundation"
-- Get the run of non-white-space at the end, if any.
set aString to current application's class "NSString"'s stringWithString:("I am a string")
set matchRange to aString's rangeOfString:("\\S++$") ¬
options:(current application's NSRegularExpressionSearch) range:({0, aString's |length|()})
if (matchRange's |length|() > 0) then
set output to aString's substringWithRange:(matchRange)
else
set output to "No match"
end if
-- Replace the first instance of "orig…" with "modified".
set anotherString to current application's class "NSString"'s stringWithString:("I am the original string")
set matchRange2 to anotherString's rangeOfString:("orig[a-z]*+") ¬
options:(current application's NSRegularExpressionSearch) range:({0, anotherString's |length|()})
if (matchRange2's |length|() > 0) then
set moreOutput to anotherString's stringByReplacingCharactersInRange:(matchRange2) withString:("modified")
else
set moreOutput to anotherString
end if
return (output as text) & linefeed & moreOutput
As an alternative to the NSString regex options used above, there's also a dedicated NSRegularExpression class:
use AppleScript version "2.4" -- OS X 10.10 (Yosemite) or later
use framework "Foundation"
-- Get the run of non-white-space at the end, if any.
set aString to current application's class "NSString"'s stringWithString:("I am a string")
set aRegex to current application's class "NSRegularExpression"'s regularExpressionWithPattern:("\\S++$") options:(0) |error|:(missing value)
set matchRange to aRegex's rangeOfFirstMatchInString:(aString) options:(0) range:({0, aString's |length|()})
if (matchRange's |length|() > 0) then
set output to aString's substringWithRange:(matchRange)
else
set output to "No match"
end if
-- Replace the first instance of "orig…" with "modified".
set anotherString to current application's class "NSString"'s stringWithString:("I am the original string")
set anotherRegex to current application's class "NSRegularExpression"'s regularExpressionWithPattern:("orig[a-z]*+") options:(0) |error|:(missing value)
set matchRange2 to anotherRegex's rangeOfFirstMatchInString:(anotherString) options:(0) range:({0, anotherString's |length|()})
if (matchRange2's |length|() > 0) then
set moreOutput to anotherString's stringByReplacingCharactersInRange:(matchRange2) withString:("modified")
else
set moreOutput to anotherString
end if
return (output as text) & linefeed & moreOutput
- Output:
The latter three scripts all return:
"string I am the modified string"
Shane Stanley has released a script library called RegexAndStuffLib, which is written in ASObjC, but provides less verbose commands for use in client scripts.
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 $tr1ng
Arturo
s: "This is a string"
if contains? s {/string$/} -> print "yes, it ends with 'string'"
replace 's {/[as]/} "x"
print s
- Output:
yes, it ends with 'string' Thix ix x xtring
AutoHotkey
MsgBox % foundpos := RegExMatch("Hello World", "World$")
MsgBox % replaced := RegExReplace("Hello World", "World$", "yourself")
AWK
AWK supports regular expressions, which are typically enclosed using slash symbols at the front and back, and the tilde regular expression binding 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)
Regular expression negation can be achieved by combining the regular expression binding operator with a logical not operator, as follows:
if (text !~ /strawberry/) {
print "Match not found"
}
BBC BASIC
Uses the gnu_regex library.
SYS "LoadLibrary", "gnu_regex.dll" TO gnu_regex%
IF gnu_regex% = 0 ERROR 100, "Cannot load gnu_regex.dll"
SYS "GetProcAddress", gnu_regex%, "regcomp" TO regcomp
SYS "GetProcAddress", gnu_regex%, "regexec" TO regexec
DIM regmatch{start%, finish%}, buffer% 256
REM Find all 'words' in a string:
teststr$ = "I love PATTERN matching!"
pattern$ = "([a-zA-Z]+)"
SYS regcomp, buffer%, pattern$, 1 TO result%
IF result% ERROR 101, "Failed to compile regular expression"
first% = 1
REPEAT
SYS regexec, buffer%, MID$(teststr$, first%), 1, regmatch{}, 0 TO result%
IF result% = 0 THEN
s% = regmatch.start%
f% = regmatch.finish%
PRINT "<" MID$(teststr$, first%+s%, f%-s%) ">"
first% += f%
ENDIF
UNTIL result%
REM Replace 'PATTERN' with 'pattern':
teststr$ = "I love PATTERN matching!"
pattern$ = "(PATTERN)"
SYS regcomp, buffer%, pattern$, 1 TO result%
IF result% ERROR 101, "Failed to compile regular expression"
SYS regexec, buffer%, teststr$, 1, regmatch{}, 0 TO result%
IF result% = 0 THEN
s% = regmatch.start%
f% = regmatch.finish%
MID$(teststr$, s%+1, f%-s%) = "pattern"
PRINT teststr$
ENDIF
SYS "FreeLibrary", gnu_regex%
- Output:
<I> <love> <PATTERN> <matching> I love pattern matching!
Bracmat
Pattern matching in Bracmat is inspired by pattern matching in Snobol. It also is quite different from regular expressions:
- Patterns in Bracmat are not greedy
- It is not possible to replace substrings, because values can never be changed
- Patterns always must match all of the subject
- Strings as well as complex data can be subjected to pattern matching
List all rational numbers smaller then 7 hidden in the string "fgsakg789/35768685432fkgha"
@("fesylk789/35768poq2art":? (#<7:?n & out$!n & ~) ?)- Output:
789/357 789/3576 789/35768 89/35 89/357 89/3576 89/35768 9/3 9/35 9/357 9/3576 9/35768 3 5 6 2
After the last number, the match expression fails.
Brat
Test
str = "I am a string"
true? str.match(/string$/)
{ p "Ends with 'string'" }
false? str.match(/^You/)
{ p "Does not start with 'You'" }Substitute
# Substitute in copy
str2 = str.sub(/ a /, " another ")
p str # original unchanged
p str2 # prints "I am another string"
# Substitute in place
str.sub!(/ a /, " another ")
p str # prints "I am another string"
# Substitute with a block
str.sub! /a/
{ match | match.upcase }
p str # prints "I Am Another string"C
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;
}
Alternative using GLib
The task is a bit easier with GLib's Perl-compatible regular expression functionality.
#include <stdio.h>
#include <glib.h>
void print_regex_match(const GRegex* regex, const char* string) {
GMatchInfo* match_info;
gboolean match = g_regex_match(regex, string, 0, &match_info);
printf(" string = '%s': %s\n", string, match ? "yes" : "no");
g_match_info_free(match_info);
}
void regex_match_demo() {
const char* pattern = "^[a-z]+$";
GError* error = NULL;
GRegex* regex = g_regex_new(pattern, 0, 0, &error);
if (regex == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
return;
}
printf("Does the string match the pattern '%s'?\n", pattern);
print_regex_match(regex, "test");
print_regex_match(regex, "Test");
g_regex_unref(regex);
}
void regex_replace_demo() {
const char* pattern = "[0-9]";
const char* input = "Test2";
const char* replace = "X";
GError* error = NULL;
GRegex* regex = g_regex_new(pattern, 0, 0, &error);
if (regex == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
return;
}
char* result = g_regex_replace_literal(regex, input, -1,
0, replace, 0, &error);
if (result == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
} else {
printf("Replace pattern '%s' in string '%s' by '%s': '%s'\n",
pattern, input, replace, result);
g_free(result);
}
g_regex_unref(regex);
}
int main() {
regex_match_demo();
regex_replace_demo();
return 0;
}
- Output:
Does the string match the pattern '^[a-z]+$'? string = 'test': yes string = 'Test': no Replace pattern '[0-9]' in string 'Test2' by 'X': 'TestX'
C#
using System;
using System.Text.RegularExpressions;
class Program {
static void Main(string[] args) {
string str = "I am a string";
if (new Regex("string$").IsMatch(str)) {
Console.WriteLine("Ends with string.");
}
str = new Regex(" a ").Replace(str, " another ");
Console.WriteLine(str);
}
}
C++
Standards earlier than C++11 can make use of Boost's Regex library via boost/regex.hpp
#include <iostream>
#include <string>
#include <iterator>
#include <regex>
int main()
{
std::regex re(".* string$");
std::string s = "Hi, I am a string";
// match the complete string
if (std::regex_match(s, re))
std::cout << "The string matches.\n";
else
std::cout << "Oops - not found?\n";
// match a substring
std::regex re2(" a.*a");
std::smatch match;
if (std::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;
std::regex_replace(std::back_inserter(dest_string),
s.begin(), s.end(),
re2,
"'m now a changed");
std::cout << dest_string << std::endl;
}
Clojure
(let [s "I am a string"]
;; match
(when (re-find #"string$" s)
(println "Ends with 'string'."))
(when-not (re-find #"^You" s)
(println "Does not start with 'You'."))
;; substitute
(println (clojure.string/replace s " a " " another "))
)
Common Lisp
Uses CL-PPCRE - Portable Perl-compatible regular expressions for Common Lisp.
(let ((string "I am a string"))
(when (cl-ppcre:scan "string$" 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'."))))
CLISP regexp engine
Clisp comes with built-in regexp matcher. On a Clisp prompt:
[1]> (regexp:match "fox" "quick fox jumps")
#S(REGEXP:MATCH :START 6 :END 9)
To find all matches, loop with different :start keyword.
Replacing text can be done with the help of REGEXP:REGEXP-SPLIT function:
[2]> (defun regexp-replace (pat repl string)
(reduce #'(lambda (x y) (string-concat x repl y))
(regexp:regexp-split pat string)))
REGEXP-REPLACE
[3]> (regexp-replace "x\\b" "-X-" "quick foxx jumps")
"quick fox-X- jumps"
D
void main() {
import std.stdio, std.regex;
immutable s = "I am a string";
// Test.
if (s.match("string$"))
"Ends with 'string'.".writeln;
// Substitute.
s.replace(" a ".regex, " another ").writeln;
}
- Output:
Ends with 'string'. I am another string
In std.string there are string functions to perform the same operations more efficiently.
Dart
RegExp regexp = new RegExp(r'\w+\!');
String capitalize(Match m) => '${m[0].substring(0, m[0].length-1).toUpperCase()}';
void main(){
String hello = 'hello hello! world world!';
String hellomodified = hello.replaceAllMapped(regexp, capitalize);
print(hello);
print(hellomodified);
}
- Output:
hello hello! world world! hello HELLO world WORLD
Delphi
Sample program that uses a regex, for translate a line of code in cpp to pascal.
program Regular_expressions;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils,
System.RegularExpressions;
const
CPP_IF = '\s*if\s*\(\s*(?<COND>.*)\s*\)\s*\{\s*return\s+(?<RETURN>.+);\s*\}';
PASCAL_IF = 'If ${COND} then result:= ${RETURN};';
var
RegularExpression: TRegEx;
str: string;
begin
str := ' if ( a < 0 ) { return -a; }';
Writeln('Expression: '#10#10, str);
if RegularExpression.Create(CPP_IF).IsMatch(str) then
begin
Writeln(#10' Is a single If in Cpp:'#10);
Writeln('Translate to Pascal:'#10);
str := RegularExpression.Create(CPP_IF).Replace(str, PASCAL_IF);
Writeln(str);
end;
readln;
end.
- Output:
Expression:
if ( a < 0 ) { return -a; }
Is a single If in Cpp:
Translate to Pascal:
If a < 0 then result:= -a;
ed
Ed s command is using regex for substitution, so the editor has built-in native support for regex.
# by Artyom Bologov
H
t0
1s/^.*string.*$/Ends with string/
2s/ a / another /
,p
Q
- Output:
$ed -s regex.input < regex.ed Newline appended Ends with string This is another string
Elixir
Elixir allows pattern matching using the ~r sigil.
str = "This is a string"
if str =~ ~r/string$/, do: IO.inspect "str ends with 'string'"
A number of modifiers can be appended to the regular expression; ~r/pattern/i, for instance, toggles case insensitivity.
str =~ ~r/this/ # => false
str =~ ~r/this/i # => true
Both Regex and String have a replace function.
str1 = ~r/a/ |> Regex.replace(str,"another")
str2 = str1 |> String.replace(~r/another/,"even another")
Regex.replace allows for a function to be used as a replacement value. A function can modify the found pattern.
str3 = ~r/another/ |> Regex.replace(str2, fn x -> "#{String.upcase(x)}" end)
- Output:
str ends with 'string'
false
true
"This is another string"
"This is even another string"
"This is even ANOTHER string"
Emacs Lisp
(let ((string "I am a string"))
(when (string-match-p "string$" string)
(message "Ends with 'string'"))
(message "%s" (replace-regexp-in-string " a " " another " string)))
- Output:
Ends with 'string' I am another string
Erlang
match() ->
String = "This is a string",
case re:run(String, "string$") 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]).
F#
open System
open System.Text.RegularExpressions
[<EntryPoint>]
let main argv =
let str = "I am a string"
if Regex("string$").IsMatch(str) then Console.WriteLine("Ends with string.")
let rstr = Regex(" a ").Replace(str, " another ")
Console.WriteLine(rstr)
0
Factor
USING: io kernel prettyprint regexp ;
IN: rosetta-code.regexp
"1000000" R/ 10+/ matches? . ! Does the entire string match the regexp?
"1001" R/ 10+/ matches? .
"1001" R/ 10+/ re-contains? . ! Does the string contain the regexp anywhere?
"blueberry pie" R/ \p{alpha}+berry/ "pumpkin" re-replace print
- Output:
t f t pumpkin pie
Forth
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]
FreeBASIC
Dim As String text = "I am a text"
If Right(text, 4) = "text" Then
Print "'" + text + "' ends with 'text'"
End If
Dim As Integer i = Instr(text, "am")
text = Left(text, i - 1) + "was" + Mid(text, i + 2)
Print "replace 'am' with 'was' = " + text
Sleep
- Output:
'I am a text' ends with 'text' replace 'am' with 'was' = I was a text
Frink
Pattern matching:
line = "My name is Inigo Montoya."
for [first, last] = line =~ %r/my name is (\w+) (\w+)/ig
{
println["First name is: $first"]
println["Last name is: $last"]
}Replacement: (Replaces in the variable line)
line =~ %s/Frank/Frink/gGambas
Click this link to run this code
Public Sub Main()
Dim sString As String = "Hello world!"
If sString Ends "!" Then Print sString & " ends with !"
If sString Begins "Hel" Then Print sString & " begins with 'Hel'"
sString = Replace(sString, "world", "moon")
Print sString
End
Output:
Hello world! ends with ! Hello world! begins with 'Hel' Hello moon!
GeneXus
Interesting link: http://wiki.gxtechnical.com/commwiki/servlet/hwiki?Regular+Expressions+%28RegEx%29,
Replacement:
&string = &string.ReplaceRegEx("^\s+|\s+$", "") // it's a trim!
&string = &string.ReplaceRegEx("Another (Match)", "Replacing $1") // Using replace groupsCheck match:
If (&string.IsMatch("regex$"))
// The string ends with "regex"
EndIfSplit RegEx:
&stringCollection = &string.SplitRegEx("^\d{2,4}")Matches:
&RegExMatchCollection = &string.Matches("(pa)tt(ern)")
For &RegExMatch In &RegExMatchCollection
&FullMatch = &RegExMatch.Value // &FullMatch contains the full pattern match: "pattern"
For &matchVarchar In &RegExMatch.Groups
// &matchVarchar contains group matches: "pa", "ern"
EndFor
EndForFlags:
s - Dot matches all (including newline)
m - multiline
i - ignore case
Using Flags Sintax: (?flags)pattern
Example:
&string = &string.ReplaceRegEx("(?si)IgnoreCase.+$", "") // Flags s and iError Handling:
&string = "abc"
&RegExMatchCollection = &string.Matches("[z-a]") // invalid pattern: z-a
&errCode = RegEx.GetLastErrCode() // returns 0 if no error and 1 if an error has occured
&errDsc = RegEx.GetLastErrDescription()Genie
[indent=4]
/* Regular expressions, in Genie */
init
var sentence = "This is a sample sentence."
try
var re = new Regex("s[ai]mple")
if re.match(sentence)
print "matched '%s' in '%s'", re.get_pattern(), sentence
var offs = 0
print("replace with 'different': %s",
re.replace(sentence, sentence.length, offs, "different"))
except err:RegexError
print err.message- Output:
prompt$ valac regularExpressions.gs prompt$ ./regularExpressions matched 's[ai]mple' in 'This is a sample sentence.' replace with 'different': This is a different sentence.
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)
}
Groovy
"Matching" Solution (it's complicated):
import java.util.regex.*;
def woodchuck = "How much wood would a woodchuck chuck if a woodchuck could chuck wood?"
def pepper = "Peter Piper picked a peck of pickled peppers"
println "=== Regular-expression String syntax (/string/) ==="
def woodRE = /[Ww]o\w+d/
def piperRE = /[Pp]\w+r/
assert woodRE instanceof String && piperRE instanceof String
assert (/[Ww]o\w+d/ == "[Ww]o\\w+d") && (/[Pp]\w+r/ == "[Pp]\\w+r")
println ([woodRE: woodRE, piperRE: piperRE])
println ()
println "=== Pattern (~) operator ==="
def woodPat = ~/[Ww]o\w+d/
def piperPat = ~piperRE
assert woodPat instanceof Pattern && piperPat instanceof Pattern
def woodList = woodchuck.split().grep(woodPat)
println ([exactTokenMatches: woodList])
println ([exactTokenMatches: pepper.split().grep(piperPat)])
println ()
println "=== Matcher (=~) operator ==="
def wwMatcher = (woodchuck =~ woodRE)
def ppMatcher = (pepper =~ /[Pp]\w+r/)
def wpMatcher = (woodchuck =~ /[Pp]\w+r/)
assert wwMatcher instanceof Matcher && ppMatcher instanceof Matcher
assert wwMatcher.toString() == woodPat.matcher(woodchuck).toString()
assert ppMatcher.toString() == piperPat.matcher(pepper).toString()
assert wpMatcher.toString() == piperPat.matcher(woodchuck).toString()
println ([ substringMatches: wwMatcher.collect { it }])
println ([ substringMatches: ppMatcher.collect { it }])
println ([ substringMatches: wpMatcher.collect { it }])
println ()
println "=== Exact Match (==~) operator ==="
def containsWoodRE = /.*/ + woodRE + /.*/
def containsPiperRE = /.*/ + piperRE + /.*/
def wwMatches = (woodchuck ==~ containsWoodRE)
assert wwMatches instanceof Boolean
def wwNotMatches = ! (woodchuck ==~ woodRE)
def ppMatches = (pepper ==~ containsPiperRE)
def pwNotMatches = ! (pepper ==~ containsWoodRE)
def wpNotMatches = ! (woodchuck ==~ containsPiperRE)
assert wwMatches && wwNotMatches && ppMatches && pwNotMatches && pwNotMatches
println ("'${woodchuck}' ${wwNotMatches ? 'does not' : 'does'} match '${woodRE}' exactly")
println ("'${woodchuck}' ${wwMatches ? 'does' : 'does not'} match '${containsWoodRE}' exactly")
- Output:
=== Regular-expression String syntax (/string/)=== [woodRE:[Ww]o\w+d, piperRE:[Pp]\w+r] === Pattern (~) operator === [exactTokenMatches:[wood, would]] [exactTokenMatches:[Peter, Piper]] === Matcher (=~) operator === [substringMatches:[wood, would, wood, wood, wood]] [substringMatches:[Peter, Piper, pepper]] [substringMatches:[]] === Exact Match (==~) operator === 'How much wood would a woodchuck chuck if a woodchuck could chuck wood?' does not match '[Ww]o\w+d' exactly 'How much wood would a woodchuck chuck if a woodchuck could chuck wood?' does match '.*[Ww]o\w+d.*' exactly
Replacement Solution (String.replaceAll()):
println woodchuck.replaceAll(/c\w+k/, "CHUCK")
- Output:
How much wood would a woodCHUCK CHUCK if a woodCHUCK could CHUCK wood?
Reusable Replacement Solution (Matcher.replaceAll()):
def ck = (woodchuck =~ /c\w+k/)
println (ck.replaceAll("CHUCK"))
println (ck.replaceAll("wind"))
println (ck.replaceAll("pile"))
println (ck.replaceAll("craft"))
println (ck.replaceAll("block"))
println (ck.replaceAll("row"))
println (ck.replaceAll("shed"))
println (ck.replaceAll("man"))
println (ck.replaceAll("work"))
println (ck.replaceAll("pickle"))
- Output:
How much wood would a woodCHUCK CHUCK if a woodCHUCK could CHUCK wood? How much wood would a woodwind wind if a woodwind could wind wood? How much wood would a woodpile pile if a woodpile could pile wood? How much wood would a woodcraft craft if a woodcraft could craft wood? How much wood would a woodblock block if a woodblock could block wood? How much wood would a woodrow row if a woodrow could row wood? How much wood would a woodshed shed if a woodshed could shed wood? How much wood would a woodman man if a woodman could man wood? How much wood would a woodwork work if a woodwork could work wood? How much wood would a woodpickle pickle if a woodpickle could pickle wood?
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
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**gIcon and Unicon
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.
- Output:
"A simple string" matches "string$" "A simple replacement"
Inform 7
Inform's regex support is similar to Perl's but with some limitations: angle brackets are used instead of square brackets, there is no multiline mode, several control characters and character classes are omitted, and backtracking is slightly less powerful.
let T be indexed text;
let T be "A simple string";
if T matches the regular expression ".*string$", say "ends with string.";
replace the regular expression "simple" in T with "replacement";
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 str
I am still a string
Note: use
open'regex'
to read the source code for the library. The comments list 6 main definitions and a dozen utility definitions.
Java
/* match entire string against a pattern */
boolean isNumber = "-1234.567".matches("-?\\d+(?:\\.\\d+)?");
/* substitute part of string using a pattern */
String reduceSpaces = "a b c d e f".replaceAll(" +", " ");
import java.util.regex.Matcher;
import java.util.regex.Pattern;
...
/* group capturing example */
Pattern pattern = Pattern.compile("(?:(https?)://)?([^/]+)/(?:([^#]+)(?:#(.+))?)?");
Matcher matcher = pattern.matcher("https://rosettacode.org/wiki/Regular_expressions#Java");
if (matcher.find()) {
String protocol = matcher.group(1);
String authority = matcher.group(2);
String path = matcher.group(3);
String fragment = matcher.group(4);
}
/* split a string using a pattern */
String[] strings = "abc\r\ndef\r\nghi".split("\r\n?");
An alternate demonstration
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'");
}
To match part of a string, or to process matches:
import java.util.regex.*;
Pattern p = Pattern.compile("a*b");
Matcher m = p.matcher(str);
while (m.find()) {
// use m.group() to extract matches
}
Substitute
String orig = "I am the original string";
String result = orig.replaceAll("original", "modified");
// result is now "I am the modified string"
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");
jq
Recent versions of jq (jq > 1.4) include PCRE regex support using the Oniguruma library.
Test:
"I am a string" | test("string$")yields: true
Substitutution:
"I am a string" | sub(" a "; " another ")yields: "I am another string"
Substitution using capture:
"abc" | sub( "(?<head>^.)(?<tail>.*)"; "\(.head)-\(.tail)")yields: "a-bc"
Jsish
/* Regular expressions, in Jsish */
var re = /s[ai]mple/;
var sentence = 'This is a sample sentence';
var matches = sentence.match(re);
if (matches.length > 0) printf('%s found in "%s" using %q\n', matches[0], sentence, re);
var replaced = sentence.replace(re, "different");
printf("replaced sentence is: %s\n", replaced);
- Output:
prompt$ jsish regularExpressions.jsi sample found in "This is a sample sentence" using "/s[ai]mple/" replaced sentence is: This is a different sentence
Julia
Julia implements Perl-compatible regular expressions (via the built-in PCRE library). To test for a match:
s = "I am a string"
if ismatch(r"string$", s)
println("'$s' ends with 'string'")
end
To perform replacements:
s = "I am a string"
s = replace(s, r" (a|an) ", " another ")
There are many other features of Julia's regular-expression support, too numerous to list here.
Kotlin
// version 1.0.6
fun main(args: Array<String>) {
val s1 = "I am the original string"
val r1 = Regex("^.*string$")
if (s1.matches(r1)) println("`$s1` matches `$r1`")
val r2 = Regex("original")
val s3 = "replacement"
val s2 = s1.replace(r2, s3)
if (s2 != s1) println("`$s2` replaces `$r2` with `$s3`")
}
- Output:
`I am the original string` matches `^.*string$` `I am the replacement string` replaces `original` with `replacement`
langur
The following examples use re2 regex literals.
There are several functions that can be used with regexes, such as match(), replace(), split(), etc. They can also be matched using the forward operator (->).
To match a string, ...
if "somestring" -> re/abc/ { ... }Or...
if x, y = submatch(re/(abc+).+?(def)/, "somestring") { ... }Or...
switch "somestring" {
case -> re/abc/: ...
...
}Or...
switch -> re/abc/ {
case "somestring": ...
...
}Substitution does not alter the original string.
replace("abcdef", re/abc/, "Y")
# result: "Ydef"Lasso
Lasso has built in support for regular expressions using ICU regexps.
local(mytext = 'My name is: Stone, Rosetta
My name is: Hippo, Campus
')
local(regexp = regexp(
-find = `(?m)^My name is: (.*?), (.*?)$`,
-input = #mytext,
-replace = `Hello! I am $2 $1`,
-ignorecase
))
while(#regexp -> find) => {^
#regexp -> groupcount > 1 ? (#regexp -> matchString(2) -> trim&) + '<br />'
^}
#regexp -> reset(-input = #mytext)
#regexp -> findall
#regexp -> reset(-input = #mytext)
'<br />'
#regexp -> replaceall
Rosetta Campus array(My name is: Stone, Rosetta, My name is: Hippo, Campus) Hello! I am Rosetta Stone Hello! I am Campus Hippo
Lua
In Lua many string manipulation methods use patterns, which offer almost the same fucntionality as regular expressions, but whose syntax differs slightly. The percent sign (%) is generally used instead of a backslash to start a character class or a reference for a match in a substitution.
test = "My name is Lua."
pattern = ".*name is (%a*).*"
if test:match(pattern) then
print("Name found.")
end
sub, num_matches = test:gsub(pattern, "Hello, %1!")
print(sub)
M2000 Interpreter
We can use COM objects so we can use VBscript.RegExp
Properties Count and List() are bound with MyMatches using smart pointer. So MyMatches can change object, and Count and List() can operate with new object.
Com objects always have one real pointer. We can't returned id (because at the exit of module or function where we create it pointer get Nothing, so properties have a "broken" pointer, and return of object returns a broken smart pointer). We can pass by reference com objects, or we can use it as Globals (until "mother" module finish). We can use WithEvent if we wish to get events. We have to make functions with object_event name (note that forms event use dot not underscore).
We can use named parameters (for Word) Try {Method Documents, "add", "", DocumentType:=WdNewWebPage as doc1}
New version using enumerator from object. Including a help SUB for displaying all functions of a COM object. Enumerators for some COM objects are number of function -4&, we can use this in place of string for the name of property.
Module CheckIt {
declare global ObjRegEx "VBscript.RegExp"
Function RegEx.Replace$(from$, what$) {
Method ObjRegEx, "Replace", from$, what$ as response$
=response$
}
Function RegEx.Test(what$) {
Method ObjRegEx, "Test", what$ as response
=response
}
Print Type$(ObjRegEx)
With ObjRegEx, "Global", True, "Pattern" as pattern$
pattern$="Mona Lisa"
Print RegEx.Test("The Mona Lisa is in the Louvre.")=true
Print RegEx.Replace$("The Mona Lisa is in the Louvre.", "La Gioconda")
Pattern$ = " {2,}"
Print "Myer Ken, Vice President, Sales and Services"
\\ Removing some spaces
Print RegEx.Replace$("Myer Ken, Vice President, Sales and Services", " ")
pattern$="(\d{3})-(\d{3})-(\d{4})"
Method ObjRegEx, "Execute", "555-123-4567, 555-943-6717" as MyMatches
Print Type$(MyMatches) ' it is a IMatchCollection2
With MyMatches, "Count" as count, "Item" as List$()
For i=0 to Count-1 : Print List$(i) : Next i
Print RegEx.Replace$("555-123-4567, 555-943-6717", "($1) $2-$3")
Pattern$ = "(\S+), (\S+)"
Print RegEx.Replace$("Myer, Ken", "$2 $1")
Method ObjRegEx, "Execute", "Myer, Ken" as MyMatches
Rem : DisplayFunctions(MyMatches)
\\ we can use Enumerator
With MyMatches, "_NewEnum" as New Matches
Rem : DisplayFunctions(Matches)
With Matches, "Value" as New item$
While Matches {
Print Item$
}
\\ Or just using the list$()
For i=0 to Count-1 : Print List$(i) : Next i
declare ObjRegEx Nothing
End
Sub DisplayFunctions(x)
Local cc=param(x), ec=each(cc)
while ec {
Print eval$(ec) ' print every function/property of object x
}
End Sub
}
Checkit
\\ internal has no pattern. There is a like operator (~) for strings which use pattern matching (using VB6 like). We can use Instr() and RInstr() for strings.
Module Internal {
what$="Mona Lisa"
Document a$="The Mona Lisa is in the Louvre."
Find a$, what$
Read FindWhere
If FindWhere<>0 then Read parNo, parlocation
\\ replace in place
Insert FindWhere, Len(what$) a$="La Gioconda"
Report a$
n$="The Mona Lisa is in the Louvre, not the Mona Lisa"
Report Replace$("Mona Lisa", "La Gioconda", n$, 1, 1) ' replace from start only one
dim a$()
a$()=Piece$("Myer, Ken",", ")
Print a$(1)+", "+a$(0)="Ken, Myer"
}
InternalM4
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
Maple
#Examples from Maple Help
StringTools:-RegMatch("^ab+bc$", "abbbbc");
StringTools:-RegMatch("^ab+bc$", "abbbbcx");
StringTools:-RegSub("a([bc]*)(c*d)", "abcd", "&-\\1-\\2");
StringTools:-RegSub("(.*)c(anad[ai])(.*)", "Maple is canadian", "\\1C\\2\\3");- Output:
true false "abcd-bc-d" "Maple is Canadian"
Mathematica /Wolfram Language
StringCases["I am a string with the number 18374 in me",RegularExpression["[0-9]+"]]
StringReplace["I am a string",RegularExpression["I\\sam"] -> "I'm"]
The in-notebook output, in order:
{18374}
I'm a string
MAXScript
samples = #("Some string 123","Example text 123","string",\
"ThisString Will Not Match","A123,333,string","123451")
samples2 = #("I am a string","Me too.")
regex = dotnetobject "System.Text.RegularExpressions.Regex" ".*\bstring*"
regex2 = dotnetobject "System.Text.RegularExpressions.Regex" "\ba\b"
clearlistener()
format "Pattern is : %\n" (regex.toString())
for i in samples do
(
if regex.ismatch(i) then
(
format "The string \"%\" matches the pattern\n" i
)
else
(
format "The string \"%\" doesn't match the pattern\n" i
)
)
-- replacement
format "Pattern is : %\n" (regex2.toString())
for i in samples2 do
(
if regex2.ismatch(i) then
(
local replaced = regex2.replace i "another"
format "The string \"%\" matched the pattern, so it was replaced: \"%\"\n" i replaced
)
else
(
format "The string \"%\" does not match the pattern\n" i
)
)- Output:
OK Pattern is : .*\bstring* OK The string "Some string 123" matches the pattern The string "Example text 123" doesn't match the pattern The string "string" matches the pattern The string "ThisString Will Not Match" doesn't match the pattern The string "A123,333,string" matches the pattern The string "123451" doesn't match the pattern OK Pattern is : \ba\b OK The string "I am a string" matched the pattern, so it was replaced: "I am another string" The string "And me too." does not match the pattern OK OK
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
MUMPS
MUMPS doesn't have a replacement functionality when using the pattern matching operator, ?. We can mimic it with $PIECE, but $PIECE doesn't work with regular expressions as an operand.
REGEXP
NEW HI,W,PATTERN,BOOLEAN
SET HI="Hello, world!",W="world"
SET PATTERN=".E1"""_W_""".E"
SET BOOLEAN=HI?@PATTERN
WRITE "Source string - '"_HI_"'",!
WRITE "Partial string - '"_W_"'",!
WRITE "Pattern string created is - '"_PATTERN_"'",!
WRITE "Match? ",$SELECT(BOOLEAN:"YES",'BOOLEAN:"No"),!
;
SET BOOLEAN=$FIND(HI,W)
IF BOOLEAN>0 WRITE $PIECE(HI,W,1)_"string"_$PIECE(HI,W,2)
QUITUsage:
USER>D REGEXP^ROSETTA Source string - 'Hello, world!' Partial string - 'world' Pattern string created is - '.E1"world".E' Match? YES Hello, string!
NetRexx
/* NetRexx */
options replace format comments java crossref symbols nobinary
import java.util.regex.
st1 = 'Fee, fie, foe, fum, I smell the blood of an Englishman'
rx1 = 'f.e.*?'
sbx = 'foo'
rx1ef = '(?i)'rx1 -- use embedded flag expression == Pattern.CASE_INSENSITIVE
-- using String's matches & replaceAll
mcm = (String st1).matches(rx1ef)
say 'String "'st1'"' 'matches pattern "'rx1ef'":' Boolean(mcm)
say
say 'Replace all occurrences of regex pattern "'rx1ef'" with "'sbx'"'
stx = Rexx
stx = (String st1).replaceAll(rx1ef, sbx)
say 'Input string: "'st1'"'
say 'Result string: "'stx'"'
say
-- using java.util.regex classes
pt1 = Pattern.compile(rx1, Pattern.CASE_INSENSITIVE)
mc1 = pt1.matcher(st1)
mcm = mc1.matches()
say 'String "'st1'"' 'matches pattern "'pt1.toString()'":' Boolean(mcm)
mc1 = pt1.matcher(st1)
say
say 'Replace all occurrences of regex pattern "'rx1'" with "'sbx'"'
sx1 = Rexx
sx1 = mc1.replaceAll(sbx)
say 'Input string: "'st1'"'
say 'Result string: "'sx1'"'
say
return
- Output:
String "Fee, fie, foe, fum, I smell the blood of an Englishman" matches pattern "(?i)f.e.*?": true Replace all occurrences of regex pattern "(?i)f.e.*?" with "foo" Input string: "Fee, fie, foe, fum, I smell the blood of an Englishman" Result string: "foo, foo, foo, fum, I smell the blood of an Englishman" String "Fee, fie, foe, fum, I smell the blood of an Englishman" matches pattern "f.e.*?": true Replace all occurrences of regex pattern "f.e.*?" with "foo" Input string: "Fee, fie, foe, fum, I smell the blood of an Englishman" Result string: "foo, foo, foo, fum, I smell the blood of an Englishman"
NewLISP
(regex "[bB]+" "AbBBbABbBAAAA") -> ("bBBb" 1 4)
Nim
import re
var s = "This is a string"
if s.find(re"string$") > -1:
echo "Ends with string."
s = s.replace(re"\ a\ ", " another ")
echo s
Objeck
use RegEx;
bundle Default {
class RegExTest {
function : Main(args : String[]) ~ Nil {
string := "I am a string";
# exact match
regex := RegEx->New(".*string");
if(regex->MatchExact(".*string")) {
"ends with 'string'"->PrintLine();
};
# replace all
regex := RegEx->New(" a ");
regex->ReplaceAll(string, " another ")->PrintLine();
}
}
}Objective-C
Test
NSString *str = @"I am a string";
NSString *regex = @".*string$";
// Note: the MATCHES operator matches the entire string, necessitating the ".*"
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.
NSRegularExpressionSearch
Test
NSString *str = @"I am a string";
if ([str rangeOfString:@"string$" options:NSRegularExpressionSearch].location != NSNotFound) {
NSLog(@"Ends with 'string'");
}
Substitute
undocumented
NSString *orig = @"I am the original string";
NSString *result = [orig stringByReplacingOccurrencesOfString:@"original"
withString:@"modified"
options:NSRegularExpressionSearch
range:NSMakeRange(0, [orig length])];
NSLog(@"%@", result);
NSRegularExpression
Test
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"string$"
options:0
error:NULL];
NSString *str = @"I am a string";
if ([regex rangeOfFirstMatchInString:str
options:0
range:NSMakeRange(0, [str length])
].location != NSNotFound) {
NSLog(@"Ends with 'string'");
}
Loop through matches
for (NSTextCheckingResult *match in [regex matchesInString:str
options:0
range:NSMakeRange(0, [str length])
]) {
// match.range gives the range of the whole match
// [match rangeAtIndex:i] gives the range of the i'th capture group (starting from 1)
}
Substitute
NSString *orig = @"I am the original string";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"original"
options:0
error:NULL];
NSString *result = [regex stringByReplacingMatchesInString:orig
options:0
range:NSMakeRange(0, [orig length])
withTemplate:@"modified"];
NSLog(@"%@", result);
OCaml
With the standard library
Test
#load "str.cma";;
let str = "I am a string";;
try
ignore(Str.search_forward (Str.regexp ".*string$") str 0);
print_endline "ends with 'string'"
with Not_found -> ()
;;
Substitute
#load "str.cma";;
let orig = "I am the original string";;
let result = Str.global_replace (Str.regexp "original") "modified" orig;;
(* result is now "I am the modified string" *)
Using Pcre
Library: ocaml-pcre
let matched pat str =
try ignore(Pcre.exec ~pat str); (true)
with Not_found -> (false)
;;
let () =
Printf.printf "matched = %b\n" (matched "string$" "I am a string");
Printf.printf "Substitute: %s\n"
(Pcre.replace ~pat:"original" ~templ:"modified" "I am the original string")
;;
Ol
; matching:
(define regex (string->regex "m/aa(bb|cc)dd/"))
(print (regex "aabbddx")) ; => true
(print (regex "aaccddx")) ; => true
(print (regex "aabcddx")) ; => false
; substitute part of a string:
(define regex (string->regex "s/aa(bb|cc)dd/HAHAHA/"))
(print (regex "aabbddx")) ; => HAHAHAx
(print (regex "aaccddx")) ; => HAHAHAx
(print (regex "aabcddx")) ; => false
ooRexx
/* Rexx */
/* Using the RxRegExp Regular Expression built-in utility class */
st1 = 'Fee, fie, foe, fum, I smell the blood of an Englishman'
rx1 = '[Ff]?e' -- unlike most regex engines, RxRegExp uses '?' instead of '.' to match any single character
sbx = 'foo'
myRE = .RegularExpression~new()
myRE~parse(rx1, MINIMAL)
mcm = myRE~pos(st1)
say 'String "'st1'"' 'matches pattern "'rx1'":' bool2string(mcm > 0)
say
-- The RxRegExp package doesn't provide a replace capability so you must roll your own
st0 = st1
loop label GREP forever
mcp = myRE~pos(st1)
if mcp > 0 then do
mpp = myRE~position
fnd = st1~substr(mcp, mpp - mcp + 1)
stx = st1~changestr(fnd, sbx, 1)
end
else leave GREP
st1 = stx
end GREP
say 'Input string: "'st0'"'
say 'Result string: "'stx'"'
return
exit
bool2string:
procedure
do
parse arg bv .
if bv then bx = 'true'
else bx = 'false'
return bx
end
exit
::requires "rxregexp.cls"
- Output:
String "Fee, fie, foe, fum, I smell the blood of an Englishman" matches pattern "[Ff]?e": true Input string: "Fee, fie, foe, fum, I smell the blood of an Englishman" Result string: "foo, foo, foo, fum, I smell the blood of an Englishman"
Oxygene
// Match and Replace part of a string using a Regular Expression
//
// Nigel Galloway - April 15th., 2012
//
namespace re;
interface
type
re = class
public
class method Main;
end;
implementation
class method re.Main;
const
myString = 'I think that I am Nigel';
var
r: System.Text.RegularExpressions.Regex;
myResult : String;
begin
r := new System.Text.RegularExpressions.Regex('(I am)|(you are)');
Console.WriteLine("{0} contains {1}", myString, r.Match(myString));
myResult := r.Replace(myString, "you are");
Console.WriteLine("{0} contains {1}", myResult, r.Match(myResult));
end;
end.Produces:
I think that I am Nigel contains I am I think that you are Nigel contains you are
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}}Pascal
// Match and Replace part of a string using a Regular Expression
//
// Nigel Galloway - April 11th., 2012
//
program RegularExpr;
uses
RegExpr;
const
myString = 'I think that I am Nigel';
myMatch = '(I am)|(you are)';
var
r : TRegExpr;
myResult : String;
begin
r := TRegExpr.Create;
r.Expression := myMatch;
write(myString);
if r.Exec(myString) then writeln(' contains ' + r.Match[0]);
myResult := r.Replace(myString, 'you are', False);
write(myResult);
if r.Exec(myResult) then writeln(' contains ' + r.Match[0]);
end.
Produces:
>RegularExpr I think that I am Nigel contains I am I think that you are Nigel contains you are
PascalABC.NET
begin
// text in tag (lazy quantification)
var s := '<tag>abc</tag> def <tag>ghi</tag>';
foreach var m in s.Matches('(?<=<tag>)(.*?)(?=</tag>)') do
Println(m.Value, m.Index);
// take words in parentheses
s := 'one two three four five';
Regex.Replace(s,'\w+','<$0>').Println;
end.
- Output:
abc 5 ghi 24 <one> <two> <three> <four> <five>
Perl
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;
In Perl 5.14+, you can return a new substituted string without altering the original string:
$string = "I am a string";
$string2 = $string =~ s/ a / another /r; # $string2 == "I am another string", $string is unaltered
print $string2;
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"
Omission of the regular expression binding operators
If regular expression matches are being made against the topic variable, it is possible to omit the regular expression binding operators:
$_ = "I like banana milkshake.";
if (/banana/) { # The regular expression binding operator is omitted
print "Match found\n";
}
Phix
with javascript_semantics include builtins\regex.e requires("1.0.2") -- (needs some recent bugfixes to regex.e for p2js) string s = "I am a string" printf(1,"\"%s\" %s with string\n",{s,iff(length(regex(`string$`,s))?"ends":"does not end")}) printf(1,"\"%s\" %s with You\n",{s,iff(length(regex(`^You`,s))?"starts":"does not start")}) ?gsub(`[A-Z]`,"abCDefG","*") ?gsub(`[A-Z]`,"abCDefGH","(&)") ?gsub(`[A-Z]+`,"abCDefGH","(&)") ?gsub(`string`,s,"replacement") s = gsub(`\ba\b`,s,"another") ?s ?gsub(`string`,s,"replacement")
- Output:
"I am a string" ends with string "I am a string" does not start with You "ab**ef*" "ab(C)(D)ef(G)(H)" "ab(CD)ef(GH)" "I am a replacement" "I am another string" "I am another replacement"
PHP
$string = 'I am a string';
# Test
if (preg_match('/string$/', $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: $string\n";
- Output:
Ends with 'string' Foud 'a' and replaced it with 'another', resulting in this string: I am another string
PicoLisp
Calling the C library
PicoLisp doesn't have built-in regex functionality. It is easy to call the native C library.
(let (Pat "a[0-9]z" String "a7z")
(use Preg
(native "@" "regcomp" 'I '(Preg (64 B . 64)) Pat 1) # Compile regex
(when (=0 (native "@" "regexec" 'I (cons NIL (64) Preg) String 0 0 0))
(prinl "String \"" String "\" matches regex \"" Pat "\"") ) ) )- Output:
String "a7z" matches pattern "a[0-9]z"
Using Pattern Matching
Regular expressions are static and inflexible. Another possibility is dynamic pattern matching, where arbitrary conditions can be programmed.
(let String "The number <7> is incremented"
(use (@A @N @Z)
(and
(match '(@A "<" @N ">" @Z) (chop String))
(format @N)
(prinl @A "<" (inc @) ">" @Z) ) ) )- Output:
The number <8> is incremented
PowerShell
"I am a string" -match '\bstr' # true
"I am a string" -replace 'a\b','no' # I am no string
By default both the -match and -replace operators are case-insensitive. They can be made case-sensitive by using the -cmatch and -creplace operators.
PureBasic
String$ = "<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
Python
import re
string = "This is a string"
if re.search('string$', string):
print("Ends with string.")
string = re.sub(" a ", " another ", string)
print(string)
R
First, define some strings.
pattern <- "string"
text1 <- "this is a matching string"
text2 <- "this does not match"
Matching with grep. The indices of the texts containing matches are returned.
grep(pattern, c(text1, text2)) # 1
Matching with regexpr. The positions of the starts of the matches are returned, along with the lengths of the matches.
regexpr(pattern, c(text1, text2))
[1] 20 -1 attr(,"match.length") [1] 6 -1
Replacement
gsub(pattern, "pair of socks", c(text1, text2))
[1] "this is a matching pair of socks" "this does not match"
Racket
#lang racket
(define s "I am a string")
(when (regexp-match? #rx"string$" s)
(displayln "Ends with 'string'."))
(unless (regexp-match? #rx"^You" s)
(displayln "Does not start with 'You'."))
(displayln (regexp-replace " a " s " another "))
Raku
(formerly Perl 6)
if 'a long string' ~~ /string$/ {
say "It ends with 'string'";
}
# substitution has a few nifty features
$_ = 'The quick Brown fox';
s:g:samecase/\w+/xxx/;
.say;
# output:
# Xxx xxx Xxx xxx
Raven
'i am a string' as strMatch:
str m/string$/
if "Ends with 'string'\n" printReplace once:
str r/ a / another / printstr r/ /_/ printReplace all:
str r/ /_/g printReplace case insensitive:
str r/ A / another /i printSplitting:
str s/ /REBOL
REBOL [
Title: "Regular Expression Matching"
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.
REXX
Rexx does not directly support the use of regular expressions as part of the language.
However, some rexx interpreters offer support for regular expressions via external function libraries or
through implementation specific extensions.
It is also possible to emulate regular expressions through appropriate coding techniques.
All of the following REXX examples are modeled after the PERL examples.
testing
/*REXX program demonstrates testing (modeled after Perl example).*/
$string="I am a string"
say 'The string is:' $string
x="string" ; if right($string,length(x))=x then say 'It ends with:' x
y="You" ; if left($string,length(y))\=y then say 'It does not start with:' y
z="ring" ; if pos(z,$string)\==0 then say 'It contains the string:' z
z="ring" ; if wordpos(z,$string)==0 then say 'It does not contain the word:' z
/*stick a fork in it, we're done.*/- Output:
The string is: I am a string It ends with: string It does not start with: You It contains the string: ring It does not contain the word: ring
substitution (destructive)
/*REXX program demonstrates substitution (modeled after Perl example).*/
$string = "I am a string"
old = " a "
new = " another "
say 'The original string is:' $string
say 'old word is:' old
say 'new word is:' new
$string = changestr(old,$string,new)
say 'The changed string is:' $string
/*stick a fork in it, we're done.*/- Output:
The original string is: I am a string old word is: a new word is: another The changed string is: I am another string
substitution (non-destructive)
/*REXX program shows non-destructive sub. (modeled after Perl example).*/
$string = "I am a string"
old = " a "
new = " another "
say 'The original string is:' $string
say 'old word is:' old
say 'new word is:' new
$string2 = changestr(old,$string,new)
say 'The original string is:' $string
say 'The changed string is:' $string2
/*stick a fork in it, we're done.*/- Output:
The original string is: I am a string old word is: a new word is: another The original string is: I am a string The changed string is: I am another string
test and substitute
/*REXX program shows test and substitute (modeled after Perl example).*/
$string = "I am a string"
old = " am "
new = " was "
say 'The original string is:' $string
say 'old word is:' old
say 'new word is:' new
if wordpos(old,$string)\==0 then
do
$string = changestr(old,$string,new)
say 'I was able to find and replace ' old " with " new
end
/*stick a fork in it, we're done.*/- Output:
The original string is: I am a string old word is: am new word is: was I was able to find and replace am with was
Some older REXXes don't have a changestr BIF, so one is included here: ───► CHANGESTR.REX.
Ring
# Project : Regular expressions
text = "I am a text"
if right(text,4) = "text"
see "'" + text +"' ends with 'text'" + nl
ok
i = substr(text,"am")
text = left(text,i - 1) + "was" + substr(text,i + 2)
see "replace 'am' with 'was' = " + text + nlOutput:
'I am a text' ends with 'text' replace 'am' with 'was' = I was a text
Ruby
Test
str = "I am a string"
p "Ends with 'string'" if str =~ /string$/
p "Does not start with 'You'" unless str =~ /^You/Substitute
str.sub(/ a /, ' another ') #=> "I am another string"
# Or:
str[/ a /] = ' another ' #=> "another"
str #=> "I am another string"Substitute using block
str.gsub(/\bam\b/) { |match| match.upcase } #=> "I AM a string"Run BASIC
string$ = "I am a string"
if right$(string$,6) = "string" then print "'";string$;"' ends with 'string'"
i = instr(string$,"am")
string$ = left$(string$,i - 1) + "was" + mid$(string$,i + 2)
print "replace 'am' with 'was' = ";string$- Output:
'I am a string' ends with 'string' replace 'am' with 'was' = I was a string
Rust
Note that Regex::new checks for a valid regex and thus returns a Result<Regex, Error>.
use regex::Regex;
fn main() {
let s = "I am a string";
if Regex::new("string$").unwrap().is_match(s) {
println!("Ends with string.");
}
println!("{}", Regex::new(" a ").unwrap().replace(s, " another "));
}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;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 groupsSearch 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 replacementSearch 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 nameUsing 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")SenseTalk
Basic example showing the use of SenseTalk's pattern language to create a pattern, test for a match, find all matches, and replace a match.
set text to "This is a story about R2D2 and C3P0 who are best friends."
set pattern to <word start, letter, digit, letter, digit, word end>
put the sixth word of text matches pattern -- (note: the sixth word is "R2D2")
put every occurrence of pattern in text
replace the second occurrence of pattern in text with "Luke"
put textOutput
True
(R2D2,C3P0)
This is a story about R2D2 and Luke who are best friends.Advanced example showing how to use capture groups within a pattern to reformat the names in a list.
set phoneList to {{
Harry Potter 98951212
Hermione Granger 59867125
Ron Weasley 56471832
}}
set wordPattern to <word start, characters, word end>
set namePattern to <start of line, {firstName: wordPattern}, space, {lastName: wordPattern}>
replace every occurrence of namePattern in phoneList with "{:lastName}, {:firstName} –"
put phoneListOutput
Potter, Harry – 98951212
Granger, Hermione – 59867125
Weasley, Ron – 56471832Shiny
str: 'I am a string'Match text:
if str.match ~string$~
say "Ends with 'string'"
endReplace text:
say str.alter ~ a ~ 'another'Sidef
Simple matching:
var str = "I am a string";
if (str =~ /string$/) {
print "Ends with 'string'\n";
}Global matching:
var str = <<'EOF';
x:Foo
y:Bar
EOF
while (var m = str=~/(\w+):(\S+)/g) {
say "#{m[0]} -> #{m[1]}";
}Substitutions:
var str = "I am a string";
# Substitute something mached by a regex
str.sub!(/ a /, ' another '); # "I am a string" => "I am another string"
# Remove something matched by a regex
str -= / \Kanother /i; # "I am another string" => "I am string"
# Global subtitution with a block
str = str.gsub(/(\w+)/, {|s1| 'x' * s1.len}); # globaly replace any word with 'xxx'
say str; # prints: 'x xx xxxxxx'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} "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.|re s s1|
re := 'm[a-z]+ing' asRegex.
s := 'this is a matching string'.
(re search: s) ifTrue: [ 'matches!' ].
s1 := re copy: s replacingMatchesWith: 'modified'.SNOBOL4
In SNOBOL4, patterns are based not on regular expressions, but are a native datatype which can be constructed, manipulated, concatenated, used in pattern expressions, stored into variables, and so forth. Patterns can be constructed ahead of time and saved in variables, and those preconstructed patterns can also reference additional pattern and data items which won't be known until actual pattern match time. Patterns can define calls to functions which will be called during actual pattern matching, and whose outcome can affect how the pattern match continues, which tentative matches will and won't be accepted, and so forth.
SNOBOL4 pattern matching is thus hugely more capable than traditional regular expressions are. An example of a pattern matching problem that would be prohibitively difficult to create as a regular expression would be to "create a pattern which matches a complete name and international postal mailing address."
SNOBOL4's "raison d'etre" is pattern matching and string manipulation (although it's also strong in data structures too). The basic statement syntax in SNOBOL4 is:
label subject pattern = object :(goto)The basic operation is to evaluate the subject, evaluate the pattern, find the pattern in the subject, evaluate the object, and then replace the portion of the subject matched by the pattern with the evaluated object. If any of those steps fails (i.e. does not succeed) then execution continues with the goto, as appropriate.
The goto can be unconditional, or can be based on whether the statement succeeded or failed (and that is the basis for all explicit transfers of control in SNOBOL4). This example finds the string "SNOBOL4" in string variable string1, and replaces it with "new SPITBOL" (SPITBOL is an implementation of SNOBOL4, basically SPITBOL is to SNOBOL4 what Turbo Pascal is to Pascal):
string1 = "The SNOBOL4 language is designed for string manipulation."
string1 "SNOBOL4" = "new SPITBOL" :s(changed)f(nochange)The following example replaces "diameter is " and a numeric value by "circumference is " and the circumference instead (it also shows creation of a pattern which matches integer or real numeric values, and storing that pattern into a variable... and then using that pattern variable later in a slightly more complicated pattern expression):
pi = 3.1415926
dd = "0123456789"
string1 = "For the first circle, the diameter is 2.5 inches."
numpat = span(dd) (("." span(dd)) | null)
string1 "diameter is " numpat . diam = "circumference is " diam * piRelatively trivial pattern matching and replacements can be attacked very effectively using regular expressions, but regular expressions (while ubiquitous) are a crippling limitation for more complicated pattern matching problems.
Standard ML
There is no regex support in the Basis Library; however, various implementations have their own support.
Test
CM.make "$/regexp-lib.cm";
structure RE = RegExpFn (
structure P = AwkSyntax
structure E = BackTrackEngine);
val re = RE.compileString "string$";
val string = "I am a string";
case StringCvt.scanString (RE.find re) string
of NONE => print "match failed\n"
| SOME match =>
let
val {pos, len} = MatchTree.root match
in
print ("matched at position " ^ Int.toString pos ^ "\n")
end;Stata
See regexm, regexr and regexs in Stata help.
scalar s="ars longa vita brevis"
* is there a vowel?
di regexm(s,"[aeiou]")
* replace the first vowel with "?"
di regexr(s,"[aeiou]","?")Swift
RegularExpressionSearch
Test
import Foundation
let str = "I am a string"
if let range = str.rangeOfString("string$", options: .RegularExpressionSearch) {
println("Ends with 'string'")
}Substitute (undocumented)
import Foundation
let orig = "I am the original string"
let result = orig.stringByReplacingOccurrencesOfString("original", withString: "modified", options: .RegularExpressionSearch)
println(result)NSRegularExpression
Test
import Foundation
if let regex = NSRegularExpression(pattern: "string$", options: nil, error: nil) {
let str = "I am a string"
if let result = regex.firstMatchInString(str, options: nil, range: NSRange(location: 0, length: count(str.utf16))) {
println("Ends with 'string'")
}
}Loop through matches
for x in regex.matchesInString(str, options: nil, range: NSRange(location: 0, length: count(str.utf16))) {
let match = x as! NSTextCheckingResult
// match.range gives the range of the whole match
// match.rangeAtIndex(i) gives the range of the i'th capture group (starting from 1)
}Substitute
import Foundation
let orig = "I am the original string"
if let regex = NSRegularExpression(pattern: "original", options: nil, error: nil) {
let result = regex.stringByReplacingMatchesInString(orig, options: nil, range: NSRange(location: 0, length: count(orig.utf16)), withTemplate: "modified")
println(result)
}Tcl
Test using regexp:
set theString "I am a string"
if {[regexp -- {string$} $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 }]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 .TXR
Search and replace: simple
Txr is not designed for sed-like filtering, but here is how to do sed -e 's/dog/cat/g':
@(collect)
@(coll :gap 0)@mismatch@{match /dog/}@(end)@suffix
@(output)
@(rep)@{mismatch}cat@(end)@suffix
@(end)
@(end)How it works is that the body of the coll uses a double-variable match:
an unbound variable followed by a regex-match variable.
The meaning of this combination is, "Search for the regular expression, and if successful, then bind all the characters whcih were skipped over by the search to the first variable, and the matching text to the second variable."
So we collect pairs: pieces of mismatching text, and pieces of text which match the regex dog.
At the end, there is usually going to be a piece of text which does not match the body, because it has no match for the regex.
Because :gap 0 is specified, the coll construct will terminate when faced with this nonmatching text, rather than skipping it in a vain search for a match, which allows @suffix to take on this trailing text.
To output the substitution, we simply spit out the mismatching texts followed by the replacement text, and then add the suffix.
Search and replace: strip comments from C source
Based on the technique of the previous example, here is a query for stripping C comments from a source file, replacing
them by a space.
Here, the "non-greedy" version of the regex Kleene operator is used,
denoted by %.
This allows for a very simple, straightforward regex which correctly matches C comments. The freeform operator allows the entire input stream to be treated as one big line, so this works across multi-line comments.
@(freeform)
@(coll :gap 0)@notcomment@{comment /[/][*].%[*][/]/}@(end)@tail
@(output)
@(rep)@notcomment @(end)@tail
@(end)Regexes in TXR Lisp
Parse regex at run time to abstract syntax:
$ txr -p '(regex-parse "a.*b")'
(compound #\a (0+ wild) #\b)Dynamically compile regex abstract syntax to regex object:
$ txr -p "(regex-compile '(compound #\a (0+ wild) #\b))"
#<sys:regex: 9c746d0>Search replace with regsub.
$ txr -p '(regsub #/a+/ "-" "baaaaaad")'
"b-d"UNIX Shell
bash and ksh implement regular expression matching via the [[ command's =~ operator.
ksh additionally allows regular expression as a flavour of general pattern matching.
Matching
s="I am a string"
if [[ $s =~ str..g$ ]]; then
echo "the string ends with 'str..g'"
fiReplacing
Given these values
s="I am the original string"
re='o.*l'
repl="modified"Can use regular expressions in parameter expansion
modified=${s/~(E)$re/$repl}
echo "$modified" # I am the modified stringhave to break apart the original string to build the modified string.
if [[ $s =~ $re ]]; then
submatch=${BASH_REMATCH[0]}
modified="${s%%$submatch*}$repl${s#*$submatch}"
echo "$modified" # I am the modified string
fiVala
void main(){
string sentence = "This is a sample sentence.";
Regex a = new Regex("s[ai]mple"); // if using \n type expressions, use triple " for string literals as easy method to escape them
if (a.match(sentence)){
stdout.printf("\"%s\" is in \"%s\"!\n", a.get_pattern(), sentence);
}
string sentence_replacement = "cat";
sentence = a.replace(sentence, sentence.length, 0, sentence_replacement);
stdout.printf("Replaced sentence is: %s\n", sentence);
}- Output:
"s[ai]mple" is in "This is a sample sentence."! Replaced sentence is: This is a cat sentence.
VBScript
Replace white spaces with line breaks.
text = "I need more coffee!!!"
Set regex = New RegExp
regex.Global = True
regex.Pattern = "\s"
If regex.Test(text) Then
WScript.StdOut.Write regex.Replace(text,vbCrLf)
Else
WScript.StdOut.Write "No matching pattern"
End If- Input:
I need more coffee!!!
- Output:
I need more coffee!!!
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)Web 68
@1Introduction.
Web 68 has access to a regular expression module
which can compile regular expressions,
use them for matching strings,
and replace strings with the matched string.
@a@<Compiler prelude@>
BEGIN
@<Declarations@>
@<Logic at the top level@>
END
@<Compiler postlude@>
@ The local compiler requires a special prelude.
@<Compiler prel...@>=
PROGRAM rosettacode regex CONTEXT VOID
USE regex,standard
@ And a special postlude.
@<Compiler post...@>=
FINISH
@1Regular expressions.
Compile a regular expression and match a string using it.
@<Decl...@>=
STRING regexp="string$";
REF REGEX rx=rx compile(regexp);
@ Declare a string for the regular expression to match.
@<Decl...@>=
STRING to match = "This is a string";
@ Define a routine to print the result of matching.
@<Decl...@>=
OP MATCH = (REF REGEX rx,STRING match)STRING:
IF rx match(rx,match,LOC SUBEXP)
THEN "matches"
ELSE "doesn't match"
FI;
@ Check whether the regular expression matches the string.
@<Logic...@>=
print(("String """,regexp,""" ",rx MATCH to match,
" string """,to match,"""",newline))
@ The end.
This program is processed by tang to produce Algol 68 code which has to be compiled by the a68toc compiler.
It's output is then compiled by gcc to produce a binary program. The script 'ca' provided with the Debian
package algol68toc requires the following command to process this program.
ca -l mod rosettacoderegex.w68
That's it. The resulting binary will print
'String "string$" matches string "This is a string"'Wren
Version 1 (Wren-pattern)
The above module allows us to do simple string pattern matching and replacement in a similar fashion to regular expressions but using a different syntax. SenseTalk's examples have been borrowed for this purpose.
import "./pattern" for Pattern
var s = "This is a story about R2D2 and C3P0 who are best friends."
var p = Pattern.new("/u/d/u/d")
var matches = p.findAll(s)
System.print("Original string:\n%(" %(s)")")
System.print("\nThe following matches were found:")
matches.each{ |m| System.print(" %(m.text) at index %(m.index)") }
System.print("\nAfter replacing the second match:")
System.print(" %(p.replace(s, "Luke", 2, 1))") // replace 2nd match with "Luke"
System.print("\nReformatted phone list example:")
var phoneList = [
"Harry Potter 98951212",
"Hermione Granger 59867125",
"Ron Weasley 56471832"
]
var p2 = Pattern.new("[+1/a] [+1/a] [=8/d]")
for (record in phoneList) {
var m = p2.find(record)
var t = m.capsText
System.print(" %(t[1]), %(t[0]) - %(t[2])")
}- Output:
Original string: This is a story about R2D2 and C3P0 who are best friends. The following matches were found: R2D2 at index 22 C3P0 at index 31 After replacing the second match: This is a story about R2D2 and Luke who are best friends. Reformatted phone list example: Potter, Harry - 98951212 Granger, Hermione - 59867125 Weasley, Ron - 56471832
Version 2 (Wren-regex)
The above module uses RE2 regular expression syntax but, since it is a wrapper for Go's 'regexp' package, it can only be used from a special embedded application and not by Wren-cli.
/* Regular_expressions_2.wren */
import "./regex" for Regex
var s = "This is a story about R2D2 and C3P0 who are best friends."
var re = Regex.compile("""[A-Z]\d[A-Z]\d""")
var matches = re.findAll(s)
var indices = re.findAllIndex(s)
System.print("Original string:\n%(" %(s)")")
System.print("\nThe following matches were found:")
for (i in 0...matches.count) {
var m = matches[i]
var ix = indices[i][0]
System.print(" %(m) at index %(ix)")
}
System.print("\nAfter replacing the second match:")
System.print(" %(re.replaceAll(s, "Luke", 2, 1))") // replace 2nd match with "Luke"
System.print("\nReformatted phone list example:")
var phoneList = [
"Harry Potter 98951212",
"Hermione Granger 59867125",
"Ron Weasley 56471832"
]
var re2 = Regex.compile("""([A-Za-z]+) ([A-Za-z]+) (\d{8})""")
for (record in phoneList) {
var m = re2.findSubmatch(record)
System.print(" %(m[2]), %(m[1]) - %(m[3])")
}- Output:
Identical to first version.
zkl
The build in RE engine is a basic one.
Strings are immutable so replacement is creation.
var re=RegExp(".*string$");
re.matches("I am a string") //-->True
var s="I am a string thing"
re=RegExp("(string)") // () means group, ie if you see it, save it
re.search(s,True) //-->True, .search(x,True) means search for a match, ie don't need .*
p,n:=re.matched[0] //.matched-->L(L(7,6),"string")
String(s[0,p],"FOO",s[p+n,*]) //-->"I am a FOO thing"
re.search(s,True); // using .matched clears it
m:=re.matched[1];
s.replace(m,"FOO"); // -->"I am a FOO thing"Using a mutable byte bucket:
var s=Data(0,Int,"I am a string thing");
re.search(s,True);
p,n:=re.matched[0];
s[p,n]="FOO";
s.text //-->"I am a FOO thing"Categories:
- Programming Tasks
- Text processing
- Regular expressions
- BASIC/Omit
- Brlcad/Omit
- EasyLang/Omit
- GUISS/Omit
- PARI/GP/Omit
- 11l
- 8th
- ABAP
- Ada
- ALGOL 68
- Amazing Hopper
- AppleScript
- Satimage.osax
- Argile
- Arturo
- AutoHotkey
- AWK
- BBC BASIC
- Bracmat
- Brat
- C
- GLib
- C sharp
- C++
- Clojure
- Common Lisp
- D
- Dart
- Delphi
- System.SysUtils
- System.RegularExpressions
- Ed
- Elixir
- Emacs Lisp
- Erlang
- F Sharp
- Factor
- Forth
- Forth Foundation Library
- FreeBASIC
- Frink
- Gambas
- GeneXus
- Genie
- Go
- Groovy
- Haskell
- HicEst
- Icon
- Unicon
- Icon Programming Library
- Inform 7
- J
- Java
- JavaScript
- Jq
- Jsish
- Julia
- Kotlin
- Langur
- Lasso
- Lua
- M2000 Interpreter
- M4
- Maple
- Mathematica
- Wolfram Language
- MAXScript
- MIRC Scripting Language
- MUMPS
- NetRexx
- NewLISP
- Nim
- Objeck
- Objective-C
- OCaml
- Ol
- OoRexx
- Oxygene
- Oz
- Pascal
- PascalABC.NET
- Perl
- Phix
- PHP
- PicoLisp
- PowerShell
- PureBasic
- Python
- R
- Racket
- Raku
- Raven
- REBOL
- REXX
- Ring
- Ruby
- Run BASIC
- Rust
- Sather
- Scala
- SenseTalk
- Shiny
- Sidef
- Slate
- Smalltalk
- SNOBOL4
- Standard ML
- Stata
- Swift
- Tcl
- Toka
- TXR
- UNIX Shell
- Vala
- VBScript
- Vedit macro language
- Web 68
- Wren
- Wren-pattern
- Wren-regex
- Zkl
- Pages with too many expensive parser function calls