Regular expressions: Difference between revisions
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=={{header|Emacs Lisp}}== |
=={{header|Emacs Lisp}}== |
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<lang |
<lang Lisp>(let ((string "I am a string")) |
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( |
(when (string-match-p "string$" string) |
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( |
(message "Ends with 'string'")) |
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(message "%s" (replace-regexp-in-string " a " " another " string)))</lang> |
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(if pos |
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(progn |
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(insert (format "%s found at position %d in: %s\n" word pos str) ) |
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(setq regex (format "^.+%s" word) ) |
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(setq str (replace-regexp-in-string regex (format "left %s" word) str) ) |
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(setq regex (format "%s.+$" word) ) |
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(setq str (replace-regexp-in-string regex (format "%s right" word) str) ) |
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(insert (format "result: %s\n" str) )) |
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(insert (format "%s not found in: %s\n" word str) ))) |
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{{out}} |
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(setq str1 "before center after" str2 "before centre after") |
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Ends with 'string' |
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(progn |
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I am another string |
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(match "center" str1) |
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(insert "\n") |
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(match "center" str2) ) |
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</lang> |
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<b>Output:</b> |
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<pre> |
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center found at position 7 in: before center after |
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result: left center right |
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center not found in: before centre after |
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</pre> |
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=={{header|Erlang}}== |
=={{header|Erlang}}== |
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Revision as of 09:59, 8 February 2022
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
<lang 11l>V string = ‘This is a string’
I re:‘string$’.search(string)
print(‘Ends with string.’)
string = string.replace(re:‘ a ’, ‘ another ’) print(string)</lang>
- Output:
Ends with string. This is another string
8th
<lang forth> "haystack" /a./ r:match . cr "haystack" /a./ "blah" s:replace! . cr </lang>
- Output:
1 hblahstblahk
ABAP
<lang 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( ). </lang>
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. <lang ada>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;</lang>
- 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.
<lang algol68>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;</lang>
- 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:<lang algol68>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, $l$))</lang>
- Output:
Dalmatians: +100 +2 Gives 101 dogs
Amazing Hopper
task 1: match a string against a regular expression (Hopper use POSIX): <lang Amazing Hopper>
- 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) </lang>
- Output:
11 18 SN12 7NY
Task 2: Hopper does not substitute using regular expressions, but using proper functions. <lang Amazing Hopper>
- 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) </lang>
- Output:
We are at another thing for this course We are at another thing for this course
AppleScript
<lang applescript>try
find text ".*string$" in "I am a string" with regexp
on error message
return message
end try
try
change "original" into "modified" in "I am the original string" with regexp
on error message
return message
end try</lang>
As from macOS 10.14 Mojave, third-party scripting additions (OSAXen) such as the Satimage OSAX are essentially unusable. (One of Apple's increasingly tight security measures.) They are allowed under very strict conditions as part of an application's own resources and Late Night Software, the developer of Script Debugger, has released a SatimageOSAX application as a stop-gap measure to allow existing Satimage-dependent scripts to be used with minimal editing until they're rewritten to use other commands.
The alternatives at the moment are to use one of the text-editing languages available through the do shell script command (AppleScript's own StandardAdditions OSAX does still work) or to use AppleScriptObjectiveC. The scripts below assume it's known that the strings will consist of just one line.
do shell script: <lang applescript>-- Get the run of non-white-space at the end, if any. try
set output to (do shell script "echo 'I am a string' | egrep -o '\\S+$'")
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</lang>
ASObjC uses ICU regex: <lang applescript>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++$") ¬
options:(current application's NSRegularExpressionSearch) range:({0, aString's |length|()})
if (matchRange's |length|() > 0) then
set output to aString's substringWithRange:(matchRange)
else
set output to "No match"
end if
-- Replace the first instance of "orig…" with "modified". set anotherString to current application's class "NSString"'s stringWithString:("I am the original string") set matchRange2 to anotherString's rangeOfString:("orig[a-z]*+") ¬
options:(current application's NSRegularExpressionSearch) range:({0, anotherString's |length|()})
if (matchRange2's |length|() > 0) then
set moreOutput to anotherString's stringByReplacingCharactersInRange:(matchRange2) withString:("modified")
else
set moreOutput to anotherString
end if
return (output as text) & linefeed & moreOutput</lang> As an alternative to the NSString regex options used above, there's also a dedicated NSRegularExpression class: <lang applescript>use AppleScript version "2.4" -- OS X 10.10 (Yosemite) or later use framework "Foundation"
-- Get the run of non-white-space at the end, if any. set aString to current application's class "NSString"'s stringWithString:("I am a string") set aRegex to current application's class "NSRegularExpression"'s regularExpressionWithPattern:("\\S++$") 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</lang>
- 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
<lang 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:)</lang>
(note that it needs to be compiled with argrt library)
- Output:
string matches $0m3 4ll0c4t3d $tr1ng
Arturo
<lang rebol>s: "This is a string"
if contains? s .regex "string$" -> print "yes, it ends with 'string'"
replace 's .regex "[as]" "x"
print s</lang>
- Output:
yes, it ends with 'string' Thix ix x xtring
AutoHotkey
<lang AutoHotkey>MsgBox % foundpos := RegExMatch("Hello World", "World$") MsgBox % replaced := RegExReplace("Hello World", "World$", "yourself")</lang>
AWK
AWK supports regular expressions, which are typically enclosed using slash symbols at the front and back, and the tilde regular expression binding operator: <lang awk>$ awk '{if($0~/[A-Z]/)print "uppercase detected"}' abc ABC uppercase detected</lang> As shorthand, a regular expression in the condition part fires if it matches an input line: <lang awk>awk '/[A-Z]/{print "uppercase detected"}' def DeF uppercase detected</lang> For substitution, the first argument can be a regular expression, while the replacement string is constant (only that '&' in it receives the value of the match): <lang awk>$ awk '{gsub(/[A-Z]/,"*");print}' abCDefG ab**ef* $ awk '{gsub(/[A-Z]/,"(&)");print}' abCDefGH ab(C)(D)ef(G)(H)</lang> This variant matches one or more uppercase letters in one round: <lang awk>$ awk '{gsub(/[A-Z]+/,"(&)");print}' abCDefGH ab(CD)ef(GH)</lang>
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. <lang bbcbasic> 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%</lang>
- 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" <lang bracmat>@("fesylk789/35768poq2art":? (#<7:?n & out$!n & ~) ?)</lang>
- Output:
789/357 789/3576 789/35768 89/35 89/357 89/3576 89/35768 9/3 9/35 9/357 9/3576 9/35768 3 5 6 2
After the last number, the match expression fails.
Brat
Test
<lang brat>str = "I am a string"
true? str.match(/string$/)
{ p "Ends with 'string'" }
false? str.match(/^You/)
{ p "Does not start with 'You'" }
</lang>
Substitute
<lang brat># 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" </lang>
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.
<lang c>#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;
}</lang>
Alternative using GLib
The task is a bit easier with GLib's Perl-compatible regular expression functionality.
<lang c>#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]+$";
GError* error = NULL;
GRegex* regex = g_regex_new(pattern, 0, 0, &error);
if (regex == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
return;
}
printf("Does the string match the pattern '%s'?\n", pattern);
print_regex_match(regex, "test");
print_regex_match(regex, "Test");
g_regex_unref(regex);
}
void regex_replace_demo() {
const char* pattern = "[0-9]";
const char* input = "Test2";
const char* replace = "X";
GError* error = NULL;
GRegex* regex = g_regex_new(pattern, 0, 0, &error);
if (regex == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
return;
}
char* result = g_regex_replace_literal(regex, input, -1,
0, replace, 0, &error);
if (result == NULL) {
fprintf(stderr, "%s\n", error->message);
g_error_free(error);
} else {
printf("Replace pattern '%s' in string '%s' by '%s': '%s'\n",
pattern, input, replace, result);
g_free(result);
}
g_regex_unref(regex);
}
int main() {
regex_match_demo(); regex_replace_demo(); return 0;
}</lang>
- Output:
Does the string match the pattern '^[a-z]+$'? string = 'test': yes string = 'Test': no Replace pattern '[0-9]' in string 'Test2' by 'X': 'TestX'
C#
<lang csharp>using System; using System.Text.RegularExpressions;
class Program {
static void Main(string[] args) {
string str = "I am a string";
if (new Regex("string$").IsMatch(str)) {
Console.WriteLine("Ends with string.");
}
str = new Regex(" a ").Replace(str, " another ");
Console.WriteLine(str);
}
}</lang>
C++
Standards earlier than C++11 can make use of Boost's Regex library via boost/regex.hpp
<lang cpp>#include <iostream>
- include <string>
- include <iterator>
- include <regex>
int main() {
std::regex re(".* string$");
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;
}</lang>
Clojure
<lang clojure>(let [s "I am a string"]
;; match (when (re-find #"string$" s) (println "Ends with 'string'.")) (when-not (re-find #"^You" s) (println "Does not start with 'You'."))
;; substitute (println (clojure.string/replace s " a " " another "))
)</lang>
Common Lisp
Uses CL-PPCRE - Portable Perl-compatible regular expressions for Common Lisp.
<lang lisp>(let ((string "I am a string"))
(when (cl-ppcre:scan "string$" string) (write-line "Ends with string")) (unless (cl-ppcre:scan "^You" string ) (write-line "Does not start with 'You'")))</lang>
Substitute
<lang lisp>(let* ((string "I am a string")
(string (cl-ppcre:regex-replace " a " string " another "))) (write-line string))</lang>
Test and Substitute
<lang lisp>(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'."))))</lang>
CLISP regexp engine
Clisp comes with built-in regexp matcher. On a Clisp prompt: <lang lisp>[1]> (regexp:match "fox" "quick fox jumps")
- S(REGEXP:MATCH :START 6 :END 9)</lang>
To find all matches, loop with different :start keyword.
Replacing text can be done with the help of REGEXP:REGEXP-SPLIT function:
<lang lisp>[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"</lang>
D
<lang d>void main() {
import std.stdio, std.regex;
immutable s = "I am a string";
// Test.
if (s.match("string$"))
"Ends with 'string'.".writeln;
// Substitute.
s.replace(" a ".regex, " another ").writeln;
}</lang>
- Output:
Ends with 'string'. I am another string
In std.string there are string functions to perform the same operations more efficiently.
Dart
<lang d>RegExp regexp = new RegExp(r'\w+\!');
String capitalize(Match m) => '${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);
}</lang>
- 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. <lang Delphi> 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:= ${RETURN};';
var
RegularExpression: TRegEx; str: string;
begin
str := ' if ( a < 0 ) { return -a; }';
Writeln('Expression: '#10#10, str);
if RegularExpression.Create(CPP_IF).IsMatch(str) then begin Writeln(#10' Is a single If in Cpp:'#10);
Writeln('Translate to Pascal:'#10);
str := RegularExpression.Create(CPP_IF).Replace(str, PASCAL_IF);
Writeln(str);
end;
readln;
end.
</lang>
- Output:
Expression:
if ( a < 0 ) { return -a; }
Is a single If in Cpp:
Translate to Pascal:
If a < 0 then result:= -a;
Elixir
Elixir allows pattern matching using the ~r sigil.
<lang Elixir>
str = "This is a string"
if str =~ ~r/string$/, do: IO.inspect "str ends with 'string'"
</lang>
A number of modifiers can be appended to the regular expression; ~r/pattern/i, for instance, toggles case insensitivity.
<lang Elixir>
str =~ ~r/this/ # => false
str =~ ~r/this/i # => true
</lang>
Both Regex and String have a replace function.
<lang Elixir>
str1 = ~r/a/ |> Regex.replace(str,"another")
str2 = str1 |> String.replace(~r/another/,"even another")
</lang>
Regex.replace allows for a function to be used as a replacement value. A function can modify the found pattern.
<lang Elixir>
str3 = ~r/another/ |> Regex.replace(str2, fn x -> "#{String.upcase(x)}" end)
</lang>
- Output:
str ends with 'string'
false
true
"This is another string"
"This is even another string"
"This is even ANOTHER string"
Emacs Lisp
<lang Lisp>(let ((string "I am a string"))
(when (string-match-p "string$" string) (message "Ends with 'string'")) (message "%s" (replace-regexp-in-string " a " " another " string)))</lang>
- Output:
Ends with 'string' I am another string
Erlang
<lang erlang>match() -> String = "This is a string", case re:run(String, "string$") 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]).</lang>
F#
<lang fsharp>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</lang>
Factor
<lang 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</lang>
- Output:
t f t pumpkin pie
Forth
Test/Match <lang forth>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]</lang>
FreeBASIC
<lang 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 </lang>
- Output:
'I am a text' ends with 'text' replace 'am' with 'was' = I was a text
Frink
Pattern matching: <lang frink> 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: $last"]
} </lang>
Replacement: (Replaces in the variable line)
<lang frink>
line =~ %s/Frank/Frink/g
</lang>
Gambas
Click this link to run this code <lang gambas>Public Sub Main() Dim sString As String = "Hello world!"
If sString Ends "!" Then Print sString & " ends with !" If sString Begins "Hel" Then Print sString & " begins with 'Hel'"
sString = Replace(sString, "world", "moon")
Print sString
End </lang> Output:
Hello world! ends with ! Hello world! begins with 'Hel' Hello moon!
GeneXus
Interesting link: http://wiki.gxtechnical.com/commwiki/servlet/hwiki?Regular+Expressions+%28RegEx%29,
Replacement:
<lang genexus>&string = &string.ReplaceRegEx("^\s+|\s+$", "") // it's a trim!
&string = &string.ReplaceRegEx("Another (Match)", "Replacing $1") // Using replace groups</lang>
Check match:
<lang genexus>If (&string.IsMatch("regex$"))
// The string ends with "regex"
EndIf</lang> Split RegEx: <lang genexus>&stringCollection = &string.SplitRegEx("^\d{2,4}")</lang> Matches: <lang genexus>&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
EndFor</lang>
Flags:
s - Dot matches all (including newline)
m - multiline
i - ignore case
Using Flags Sintax: (?flags)pattern
Example:
<lang genexus>&string = &string.ReplaceRegEx("(?si)IgnoreCase.+$", "") // Flags s and i</lang>
Error Handling:
<lang genexus>&string = "abc"
&RegExMatchCollection = &string.Matches("[z-a]") // invalid pattern: z-a
&errCode = RegEx.GetLastErrCode() // returns 0 if no error and 1 if an error has occured
&errDsc = RegEx.GetLastErrDescription()</lang>
Genie
<lang genie>[indent=4] /* Regular expressions, in Genie */
init
var sentence = "This is a sample sentence."
try
var re = new Regex("s[ai]mple")
if re.match(sentence)
print "matched '%s' in '%s'", re.get_pattern(), sentence
var offs = 0
print("replace with 'different': %s",
re.replace(sentence, sentence.length, offs, "different"))
except err:RegexError
print err.message</lang>
- Output:
prompt$ valac regularExpressions.gs prompt$ ./regularExpressions matched 's[ai]mple' in 'This is a sample sentence.' replace with 'different': This is a different sentence.
Go
<lang 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)
}</lang>
Groovy
"Matching" Solution (it's complicated): <lang groovy>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")</lang>
- 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()): <lang groovy>println woodchuck.replaceAll(/c\w+k/, "CHUCK")</lang>
- Output:
How much wood would a woodCHUCK CHUCK if a woodCHUCK could CHUCK wood?
Reusable Replacement Solution (Matcher.replaceAll()): <lang groovy>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"))</lang>
- 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 <lang haskell>import Text.Regex
str = "I am a string"
case matchRegex (mkRegex ".*string$") str of
Just _ -> putStrLn $ "ends with 'string'" Nothing -> return ()</lang>
Substitute <lang haskell>import Text.Regex
orig = "I am the original string" result = subRegex (mkRegex "original") orig "modified" putStrLn $ result</lang>
HicEst
<lang 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</lang>
Icon 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.
<lang Icon>procedure main()
s := "A simple string" p := "string$" # regular expression
s ? write(image(s),if ReFind(p) then " matches " else " doesn't match ",image(p))
s[j := ReFind(p,s):ReMatch(p,s,j)] := "replacement" write(image(s)) end
link regexp # link to IPL regexp </lang>
- Output:
"A simple string" matches "string$" "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.
<lang inform7>let T be indexed text; let T be "A simple string"; if T matches the regular expression ".*string$", say "ends with string."; replace the regular expression "simple" in T with "replacement";</lang>
J
J's regex support is built on top of PCRE.
<lang j>load'regex' NB. Load regex library str =: 'I am a string' NB. String used in examples.</lang>
Matching:
<lang j> '.*string$' rxeq str NB. 1 is true, 0 is false 1</lang>
Substitution:
<lang j> ('am';'am still') rxrplc str I am still a string</lang>
Note: use<lang J> open'regex'</lang> to read the source code for the library. The comments list 6 main definitions and a dozen utility definitions.
Java
Test
<lang java>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'");
}</lang>
To match part of a string, or to process matches: <lang java>import java.util.regex.*; Pattern p = Pattern.compile("a*b"); Matcher m = p.matcher(str); while (m.find()) {
// use m.group() to extract matches
}</lang>
Substitute
<lang java>String orig = "I am the original string"; String result = orig.replaceAll("original", "modified"); // result is now "I am the modified string"</lang>
JavaScript
Test/Match <lang javascript>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);</lang>
Substitute <lang javascript>var subject = "Hello world!";
// Perform a string replacement // newSubject == "Replaced!" var newSubject = subject.replace(re_PatternToMatch, "Replaced");</lang>
jq
Recent versions of jq (jq > 1.4) include PCRE regex support using the Oniguruma library.
Test: <lang jq>"I am a string" | test("string$") </lang> yields: true
Substitutution: <lang jq>"I am a string" | sub(" a "; " another ")</lang> yields: "I am another string"
Substitution using capture: <lang jq>"abc" | sub( "(?<head>^.)(?<tail>.*)"; "\(.head)-\(.tail)")</lang> yields: "a-bc"
Jsish
<lang javascript>/* 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);</lang>
- 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: <lang julia>s = "I am a string" if ismatch(r"string$", s)
println("'$s' ends with 'string'")
end</lang> To perform replacements: <lang julia>s = "I am a string" s = replace(s, r" (a|an) ", " another ")</lang> There are many other features of Julia's regular-expression support, too numerous to list here.
Kotlin
<lang scala>// 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`")
}</lang>
- Output:
`I am the original string` matches `^.*string$` `I am the replacement string` replaces `original` with `replacement`
langur
Langur uses semi-integreted regex. The following examples use re2 regex literals.
There are several functions that can be used with regexes, such as match(), replace(), split(), etc. They can also be matched in a given expression test.
To match a string, ... <lang langur>if matching(re/abc/, "somestring") { ... }</lang>
Or...
<lang langur>if val .x, .y = submatch(re/(abc+).+?(def)/, "somestring") { ... }</lang>
Prior to 0.10, multi-variable declaration/assignment would use parentheses around variable names and values. <lang langur>if val (.x, .y) = submatch(re/(abc+).+?(def)/, "somestring") { ... }</lang>
Or... <lang langur>given "somestring" {
case re/abc/: ... ...
}</lang>
Or... <lang langur>given re/abc/ {
case "somestring": ... ...
}</lang>
Substitution does not alter the original string. <lang langur>replace("abcdef", re/abc/, "Y")
- result: "Ydef"</lang>
Lasso
Lasso has built in support for regular expressions using ICU regexps. <lang Lasso>local(mytext = 'My name is: Stone, Rosetta My name is: Hippo, Campus ')
local(regexp = regexp( -find = `(?m)^My name is: (.*?), (.*?)$`, -input = #mytext, -replace = `Hello! I am $2 $1`, -ignorecase ))
while(#regexp -> find) => {^
#regexp -> groupcount > 1 ? (#regexp -> matchString(2) -> trim&) + '
'
^}
- regexp -> reset(-input = #mytext)
- regexp -> findall
- regexp -> reset(-input = #mytext)
'
'
- regexp -> replaceall</lang>
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.
<lang lua>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)</lang>
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.
<lang M2000 Interpreter> 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"
} Internal </lang>
M4
<lang M4>regexp(`GNUs not Unix', `\<[a-z]\w+') regexp(`GNUs not Unix', `\<[a-z]\(\w+\)', `a \& b \1 c')</lang>
- Output:
5 a not b ot c
Maple
<lang 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");</lang>
- Output:
true false "abcd-bc-d" "Maple is Canadian"
Mathematica/Wolfram Language
<lang Mathematica>StringCases["I am a string with the number 18374 in me",RegularExpression["[0-9]+"]] StringReplace["I am a string",RegularExpression["I\\sam"] -> "I'm"]</lang> The in-notebook output, in order:
{18374}
I'm a string
MAXScript
<lang 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 ) ) </lang>
- 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
<lang mirc>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)
}</lang>
- 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 $PIECE doesn't work with regular expressions as an operand.
<lang MUMPS>REGEXP
NEW HI,W,PATTERN,BOOLEAN SET HI="Hello, world!",W="world" SET PATTERN=".E1"""_W_""".E" SET BOOLEAN=HI?@PATTERN WRITE "Source string - '"_HI_"'",! WRITE "Partial string - '"_W_"'",! WRITE "Pattern string created is - '"_PATTERN_"'",! WRITE "Match? ",$SELECT(BOOLEAN:"YES",'BOOLEAN:"No"),! ; SET BOOLEAN=$FIND(HI,W) IF BOOLEAN>0 WRITE $PIECE(HI,W,1)_"string"_$PIECE(HI,W,2) QUIT</lang>
Usage:
USER>D REGEXP^ROSETTA Source string - 'Hello, world!' Partial string - 'world' Pattern string created is - '.E1"world".E' Match? YES Hello, string!
NetRexx
<lang 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 </lang>
- 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
<lang NewLISP >(regex "[bB]+" "AbBBbABbBAAAA") -> ("bBBb" 1 4)</lang>
Nim
<lang nim>import re
var s = "This is a string"
if s.find(re"string$") > -1:
echo "Ends with string."
s = s.replace(re"\ a\ ", " another ") echo s</lang>
Objeck
<lang objeck> use RegEx;
bundle Default {
class RegExTest {
function : Main(args : String[]) ~ Nil {
string := "I am a string";
# exact match
regex := RegEx->New(".*string");
if(regex->MatchExact(".*string")) {
"ends with 'string'"->PrintLine();
};
# replace all
regex := RegEx->New(" a ");
regex->ReplaceAll(string, " another ")->PrintLine();
}
}
} </lang>
Objective-C
Test
<lang objc>NSString *str = @"I am a string"; NSString *regex = @".*string$";
// 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'");
}</lang> Unfortunately this method cannot find the location of the match or do substitution.
NSRegularExpressionSearch
Test
<lang objc>NSString *str = @"I am a string"; if ([str rangeOfString:@"string$" options:NSRegularExpressionSearch].location != NSNotFound) {
NSLog(@"Ends with 'string'");
}</lang>
Substitute
undocumented
<lang objc>NSString *orig = @"I am the original string"; NSString *result = [orig stringByReplacingOccurrencesOfString:@"original"
withString:@"modified"
options:NSRegularExpressionSearch
range:NSMakeRange(0, [orig length])];
NSLog(@"%@", result);</lang>
NSRegularExpression
Test <lang objc>NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"string$"
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'");
}</lang>
Loop through matches <lang objc>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)
}</lang>
Substitute <lang objc>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);</lang>
OCaml
With the standard library
Test <lang ocaml>#load "str.cma";; let str = "I am a string";; try
ignore(Str.search_forward (Str.regexp ".*string$") str 0); print_endline "ends with 'string'"
with Not_found -> ()
- </lang>
Substitute <lang ocaml>#load "str.cma";; let orig = "I am the original string";; let result = Str.global_replace (Str.regexp "original") "modified" orig;; (* result is now "I am the modified string" *)</lang>
Using Pcre
Library: ocaml-pcre
<lang ocaml>let matched pat str =
try ignore(Pcre.exec ~pat str); (true) with Not_found -> (false)
let () =
Printf.printf "matched = %b\n" (matched "string$" "I am a string"); Printf.printf "Substitute: %s\n" (Pcre.replace ~pat:"original" ~templ:"modified" "I am the original string")
- </lang>
Ol
<lang scheme>
- 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
</lang>
ooRexx
<lang 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"
</lang>
- 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
<lang 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. </lang> Produces:
I think that I am Nigel contains I am I think that you are Nigel contains you are
Oz
<lang 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}}</lang>
Pascal
<lang 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. </lang> Produces:
>RegularExpr I think that I am Nigel contains I am I think that you are Nigel contains you are
Perl
Test <lang perl>$string = "I am a string"; if ($string =~ /string$/) {
print "Ends with 'string'\n";
}
if ($string !~ /^You/) {
print "Does not start with 'You'\n";
}</lang>
Substitute
<lang perl>$string = "I am a string";
$string =~ s/ a / another /; # makes "I am a string" into "I am another string"
print $string;</lang>
In Perl 5.14+, you can return a new substituted string without altering the original string: <lang perl>$string = "I am a string"; $string2 = $string =~ s/ a / another /r; # $string2 == "I am another string", $string is unaltered print $string2;</lang>
Test and Substitute
<lang perl>$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";
}</lang>
Options
<lang perl># 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)
$string =~ s/i/u/ig; # would change "I am a string" into "u am a strung"</lang>
Omission of the regular expression binding operators
If regular expression matches are being made against the topic variable, it is possible to omit the regular expression binding operators:
<lang perl>$_ = "I like banana milkshake."; if (/banana/) { # The regular expression binding operator is omitted
print "Match found\n";
}</lang>
Phix
<lang Phix>include builtins\regex.e string s = "I am a string" printf(1,"\"%s\" %s with string\n",{s,iff(length(regex(`string$`,s))?"ends":"does not end")}) printf(1,"\"%s\" %s with You\n",{s,iff(length(regex(`^You`,s))?"starts":"does not start")}) ?gsub(`[A-Z]`,"abCDefG","*") ?gsub(`[A-Z]`,"abCDefGH","(&)") ?gsub(`[A-Z]+`,"abCDefGH","(&)") ?gsub(`string`,s,"replacement") s = gsub(`\ba\b`,s,"another") ?s ?gsub(`string`,s,"replacement")</lang>
- Output:
"I am a string" ends with string "I am a string" does not start with You "ab**ef*" "ab(C)(D)ef(G)(H)" "ab(CD)ef(GH)" "I am a replacement" "I am another string" "I am another replacement"
PHP
<lang php>$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: $string\n";</lang>
- Output:
Ends with 'string' Foud 'a' and replaced it with 'another', resulting in this string: I am another string
PicoLisp
Calling the C library
PicoLisp doesn't have built-in regex functionality. It is easy to call the native C library. <lang PicoLisp>(let (Pat "a[0-9]z" String "a7z")
(use Preg
(native "@" "regcomp" 'I '(Preg (64 B . 64)) Pat 1) # Compile regex
(when (=0 (native "@" "regexec" 'I (cons NIL (64) Preg) String 0 0 0))
(prinl "String \"" String "\" matches regex \"" Pat "\"") ) ) )</lang>
- Output:
String "a7z" matches pattern "a[0-9]z"
Using Pattern Matching
Regular expressions are static and inflexible. Another possibility is dynamic pattern matching, where arbitrary conditions can be programmed. <lang PicoLisp>(let String "The number <7> is incremented"
(use (@A @N @Z)
(and
(match '(@A "<" @N ">" @Z) (chop String))
(format @N)
(prinl @A "<" (inc @) ">" @Z) ) ) )</lang>
- Output:
The number <8> is incremented
PowerShell
<lang powershell>"I am a string" -match '\bstr' # true
"I am a string" -replace 'a\b','no' # I am no string</lang>
By default both the -match and -replace operators are case-insensitive. They can be made case-sensitive by using the -cmatch and -creplace operators.
PureBasic
<lang PureBasic>String$ = "<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</lang>
Python
<lang python>import re
string = "This is a string"
if re.search('string$', string):
print("Ends with string.")
string = re.sub(" a ", " another ", string) print(string)</lang>
R
First, define some strings. <lang R>pattern <- "string" text1 <- "this is a matching string" text2 <- "this does not match"</lang> Matching with grep. The indices of the texts containing matches are returned. <lang R>grep(pattern, c(text1, text2)) # 1</lang> Matching with regexpr. The positions of the starts of the matches are returned, along with the lengths of the matches. <lang R>regexpr(pattern, c(text1, text2))</lang>
[1] 20 -1 attr(,"match.length") [1] 6 -1
Replacement <lang R>gsub(pattern, "pair of socks", c(text1, text2))</lang>
[1] "this is a matching pair of socks" "this does not match"
Racket
<lang racket>
- lang racket
(define s "I am a string")
(when (regexp-match? #rx"string$" s)
(displayln "Ends with 'string'."))
(unless (regexp-match? #rx"^You" s)
(displayln "Does not start with 'You'."))
(displayln (regexp-replace " a " s " another ")) </lang>
Raku
(formerly Perl 6) <lang perl6>if 'a long string' ~~ /string$/ {
say "It ends with 'string'";
}
- substitution has a few nifty features
$_ = 'The quick Brown fox'; s:g:samecase/\w+/xxx/; .say;
- output:
- Xxx xxx Xxx xxx
</lang>
Raven
<lang raven>'i am a string' as str</lang>
Match:
<lang raven>str m/string$/ if "Ends with 'string'\n" print</lang>
Replace once:
<lang raven>str r/ a / another / print</lang> <lang raven>str r/ /_/ print</lang>
Replace all:
<lang raven>str r/ /_/g print</lang>
Replace case insensitive:
<lang raven>str r/ A / another /i print</lang>
Splitting:
<lang raven>str s/ /</lang>
REBOL
<lang 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]</lang>
- 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
<lang rexx>/*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.*/</lang>
- 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)
<lang rexx>/*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.*/</lang>
- 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)
<lang rexx>/*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.*/</lang>
- 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
<lang rexx>/*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.*/</lang>
- 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
<lang 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 + nl </lang> Output:
'I am a text' ends with 'text' replace 'am' with 'was' = I was a text
Ruby
Test <lang ruby>str = "I am a string" p "Ends with 'string'" if str =~ /string$/ p "Does not start with 'You'" unless str =~ /^You/</lang>
Substitute <lang ruby>str.sub(/ a /, ' another ') #=> "I am another string"
- Or:
str[/ a /] = ' another ' #=> "another" str #=> "I am another string"</lang>
Substitute using block <lang ruby>str.gsub(/\bam\b/) { |match| match.upcase } #=> "I AM a string"</lang>
Run BASIC
<lang runbasic>string$ = "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$ </lang>
- 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>.
<lang Rust>use regex::Regex;
fn main() {
let s = "I am a string";
if Regex::new("string$").unwrap().is_match(s) {
println!("Ends with string.");
}
println!("{}", Regex::new(" a ").unwrap().replace(s, " another "));
}</lang>
Sather
Sather understands POSIX regular expressions.
<lang sather>class MAIN is
-- we need to implement the substitution regex_subst(re:REGEXP, s, sb:STR):STR is from, to:INT; re.match(s, out from, out to); if from = -1 then return s; end; return s.head(from) + sb + s.tail(s.size - to); end;
main is
s ::= "I am a string";
re ::= REGEXP::regexp("string$", 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;</lang>
Scala
Define <lang Scala>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</lang>
Search and replace with string methods: <lang scala>"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</lang>
Search with regex methods: <lang scala>"\\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</lang>
Using pattern matching with regex: <lang Scala>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)</lang>
Replacing with regex: <lang Scala>Bottles2 replaceFirstIn ("99 bottles of beer", "98 bottles of beer") Bottles3 replaceAllIn ("99 bottles of beer", "98 bottles of beer")</lang>
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. <lang sensetalk> 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 text </lang> Output <lang sensetalk> True (R2D2,C3P0) This is a story about R2D2 and Luke who are best friends. </lang>
Advanced example showing how to use capture groups within a pattern to reformat the names in a list. <lang sensetalk> 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 phoneList </lang> Output <lang sensetalk> Potter, Harry – 98951212 Granger, Hermione – 59867125 Weasley, Ron – 56471832 </lang>
Shiny
<lang shiny>str: 'I am a string'</lang>
Match text: <lang shiny>if str.match ~string$~
say "Ends with 'string'"
end</lang>
Replace text: <lang shiny>say str.alter ~ a ~ 'another'</lang>
Sidef
Simple matching: <lang ruby>var str = "I am a string"; if (str =~ /string$/) {
print "Ends with 'string'\n";
}</lang>
Global matching: <lang ruby>var str = <<'EOF';
x:Foo y:Bar
EOF
while (var m = str=~/(\w+):(\S+)/g) {
say "#{m[0]} -> #{m[1]}";
}</lang>
Substitutions: <lang ruby>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'</lang>
Slate
This library is still in its early stages. There isn't currently a feature to replace a substring.
<lang slate>
'http://slatelanguage.org/test/page?query' =~ '^(([^:/?#]+)\\:)?(//([^/?#]*))?([^?#]*)(\\?([^#]*))?(#(.*))?'.
" ==> {'http:'. 'http'. '//slatelanguage.org'. 'slatelanguage.org'. '/test/page'. '?query'. 'query'. Nil} " </lang>
Smalltalk
<lang 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.</lang>
<lang smalltalk> |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'. </lang>
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:
<lang snobol4>label subject pattern = object :(goto)</lang>
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):
<lang snobol4> string1 = "The SNOBOL4 language is designed for string manipulation."
string1 "SNOBOL4" = "new SPITBOL" :s(changed)f(nochange)</lang>
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):
<lang snobol4> 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 * pi</lang>
Relatively 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 <lang sml>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;</lang>
Stata
See regexm, regexr and regexs in Stata help.
<lang stata>scalar s="ars longa vita brevis"
- is there a vowel?
di regexm(s,"[aeiou]")
- replace the first vowel with "?"
di regexr(s,"[aeiou]","?")</lang>
Swift
RegularExpressionSearch
Test <lang swift>import Foundation
let str = "I am a string" if let range = str.rangeOfString("string$", options: .RegularExpressionSearch) {
println("Ends with 'string'")
}</lang>
Substitute (undocumented) <lang swift>import Foundation
let orig = "I am the original string" let result = orig.stringByReplacingOccurrencesOfString("original", withString: "modified", options: .RegularExpressionSearch) println(result)</lang>
NSRegularExpression
Test <lang swift>import Foundation
if let regex = NSRegularExpression(pattern: "string$", 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'")
}
}</lang>
Loop through matches <lang swift> 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) }</lang>
Substitute <lang swift>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)
}</lang>
Tcl
Test using regexp:
<lang tcl>set theString "I am a string"
if {[regexp -- {string$} $theString]} {
puts "Ends with 'string'"
}
if {![regexp -- {^You} $theString]} {
puts "Does not start with 'You'"
}</lang>
Extract substring using regexp
<lang tcl>set theString "This string has >123< a number in it"
if {[regexp -- {>(\d+)<} $theString -> number]} {
puts "Contains the number $number"
}</lang>
Substitute using regsub
<lang tcl>set theString = "I am a string"
puts [regsub -- { +a +} $theString { another }]</lang>
Toka
Toka's regular expression library allows for matching, but does not yet provide for replacing elements within strings.
<lang toka>#! 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 .</lang>
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':
<lang txr>@(collect) @(coll :gap 0)@mismatch@{match /dog/}@(end)@suffix @(output) @(rep)@{mismatch}cat@(end)@suffix @(end) @(end)</lang>
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.
<lang txr>@(freeform) @(coll :gap 0)@notcomment@{comment /[/][*].%[*][/]/}@(end)@tail @(output) @(rep)@notcomment @(end)@tail @(end)</lang>
Regexes in TXR Lisp
Parse regex at run time to abstract syntax:
<lang sh>$ txr -p '(regex-parse "a.*b")' (compound #\a (0+ wild) #\b)</lang>
Dynamically compile regex abstract syntax to regex object:
<lang sh>$ txr -p "(regex-compile '(compound #\a (0+ wild) #\b))"
- <sys:regex: 9c746d0></lang>
Search replace with regsub.
<lang sh>$ txr -p '(regsub #/a+/ "-" "baaaaaad")' "b-d"</lang>
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
<lang bash>s="I am a string" if $s =~ str..g$ ; then
echo "the string ends with 'str..g'"
fi</lang>
Replacing
Given these values <lang bash>s="I am the original string" re='o.*l' repl="modified"</lang>
Can use regular expressions in parameter expansion <lang bash>modified=${s/~(E)$re/$repl} echo "$modified" # I am the modified string</lang>
have to break apart the original string to build the modified string. <lang bash>if $s =~ $re ; then
submatch=${BASH_REMATCH[0]}
modified="${s%%$submatch*}$repl${s#*$submatch}"
echo "$modified" # I am the modified string
fi</lang>
Vala
<lang vala> 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);
} </lang>
- 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. <lang vb>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</lang>
- 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: <lang vedit>if (Match(".* string$", REGEXP)==0) {
Statline_Message("This line ends with 'string'")
}</lang>
Search for a pattern: <lang vedit>if (Search("string$", REGEXP+NOERR)) {
Statline_Message("'string' at and of line found")
}</lang>
Replace: <lang vedit>Replace(" a ", " another ", REGEXP+NOERR)</lang>
Web 68
<lang web68>@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"'</lang>
Wren
Wren doesn't have regular expressions as such but the above module allows us to do simple string pattern matching and replacement in a similar fashion. SenseTalk's examples have been borrowed for this purpose. <lang ecmascript>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])")
}</lang>
- 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
zkl
The build in RE engine is a basic one.
Strings are immutable so replacement is creation.
<lang zkl>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"</lang>
Using a mutable byte bucket: <lang zkl>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"</lang>
- Programming Tasks
- Text processing
- Regular expressions
- BASIC/Omit
- Brlcad/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
- 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
- Perl
- Phix
- PHP
- PicoLisp
- PowerShell
- PureBasic
- Python
- R
- Racket
- Raku
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- 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
- Zkl