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Regex

Matching

Check if a string matches a regular expression

Display "ok" if "Hello" matches /[A-Z][a-z]+/

clojure

(if (re-matches #"[A-Z][a-z]+" "Hello")
(println "ok"))

cpp

if ((gcnew Regex("[A-Z][a-z]+"))->IsMatch("Hello")) Console::WriteLine("ok");

if (Regex::IsMatch("Hello", "[A-Z][a-z]+")) Console::WriteLine("ok");

Regex^ rx = gcnew Regex("[A-Z][a-z]+");
if (rx->IsMatch("Hello")) Console::WriteLine("ok");

cmatch what;
if (regex_match("Hello", what, regex("[A-Z][a-z]+")))
cout << "ok" << endl;

erlang

String = "Hello", Regexp = "[A-Z][a-z]+",
is_match(String, Regexp) andalso (begin io:format("ok~n"), true end).

case re:run("Hello", "[A-Z][a-z]+") of {match, _} -> ok end.

fantom

if (Regex<|[A-Z][a-z]+|>.matches("Hello"))
echo("ok")

fsharp

if (Regex.IsMatch("Hello", "[A-Z][a-z]+")) then printfn "ok"

groovy

if ("Hello" =~ /[A-Z][a-z]+/) println 'ok'

if ("Hello".find(/[A-Z][a-z]+/)) println 'ok'

// with precompiled regex
def regex = ~/[A-Z][a-z]+/
if ("Hello".find(regex)) println 'ok'

// with precompiled regex
def regex = ~/[A-Z][a-z]+/
if ("Hello".matches(regex)) println 'ok'

if ("Hello".matches("[A-Z][a-z]+")) println 'ok'

haskell

import Text.Regex.Posix
main = if "Hello" =~ "[A-Z][a-z]+" then putStrLn "OK" else return ()

java

if ("Hello".matches("[A-Z][a-z]+")) {
System.out.println("ok");
}

ocaml

if Str.string_match (Str.regexp "[A-Z][a-z]+") "Hello" 0
then print_string "ok";;

perl

print 'ok' if ('Hello' =~ /[A-Z][a-z]+/);

php

if(ereg('[A-Za-z]+', 'Hello')) {
echo "ok";
}

if(preg_match('/[A-Za-z]+/', 'Hello')>0) {
echo "ok";
}

python

found = re.match(r'[A-Z][a-z]+', 'Hello')
if found:
print 'ok'

ruby

puts "ok" if ("Hello"=~/^[A-Z][a-z]+$/)

scala

if ("Hello".matches("[A-Z][a-z]+")) println("ok")

Check if a string matches with groups

Display "two" if "one two three" matches /one (.*) three/

clojure

(if-let [groups (re-matches #"one (.*) three" "one two three")]
(println (second groups)))

cpp

Match^ match = Regex::Match("one two three", "one (.*) three");
if (match->Success) Console::WriteLine("{0}", match->Groups[1]->Captures[0]);

cmatch what;
if (regex_match("one two three", what, regex("one (.*) three")))
cout << what[1] << endl;

erlang

case re:run("one two three", "one (.*) three", [{capture, [1], list}]) of {match, Res} -> hd(Res) end.

fantom

m := Regex<|one (.*) three|>.matcher("one two three")
if (m.matches)
echo("${m.group(1)}")

fsharp

let regmatch = (Regex.Match("one two three", "one (.*) three"))
if regmatch.Success then (printfn "%s" (regmatch.Groups.[1].Captures.[0].ToString()))

groovy

matcher = ("one two three" =~ /one (.*) three/)
if (matcher) println matcher[0][1]

match = "one two three".find("one (.*) three") { it[1] }
if (match) println match

haskell

import Text.Regex
main = case matchRegex (mkRegex "one (.*) three") "one two three" of
Nothing -> return ()
Just (x:_) -> putStrLn x

java

Pattern pattern = Pattern.compile("one (.*) three");
Matcher matcher = pattern.matcher("one two three");
if (matcher.matches()) {
System.out.println(matcher.group(1));
}

ocaml

#load "str.cma" ;;

let s = "one two three" in
if Str.string_match (Str.regexp "one \$.*\$ three") s 0 then
print_string (Str.matched_group 1 s)

perl

print $1 if "one two three"=~/^one (.*) three$/

php

preg_match('/one (.*) three/', 'one two three', $matches);
echo $matches[1];

ereg('one (.*) three', 'one two three', $regs);
echo $regs[1];

python

match = re.match(r'one (.*) three', 'one two three')
if match:
print match.group(1)

ruby

puts $1 if "one two three"=~/^one (.*) three$/

scala

val m = Pattern.compile("one (.*) three").matcher("one two three")
if (m.matches) println(m.group(1))

Searching

Check if a string contains a match to a regular expression

Display "ok" if "abc 123 @#$" matches /\d+/

clojure

(if (re-find #"\d+" "abc 123 @#$")
(println "ok"))

cpp

if (Regex::IsMatch("abc 123 @#$", "\\d+")) Console::WriteLine("ok");

erlang

% Erlang uses 'egrep'-compatible regular expressions, so shortcuts like '\d' not supported
String = "abc 123 @#$", Regexp = "[0-9]+",
is_match(String, Regexp) andalso (begin io:format("ok~n"), true end).

case re:run("abc 123 @#$", "\\d+") of {match, _} -> ok end.

fantom

m := Regex<|\d+|>.matcher("abc 123 @#\$")
if (m.find)
echo("ok")

fsharp

if (Regex.IsMatch("abc 123 @#$", "\\d+")) then printfn "ok"

groovy

if ('abc 123 @#$' =~ /\d+/) println 'ok'

if ('abc 123 @#$'.find(/\d+/)) println 'ok'

haskell

import Text.Regex
main = case matchRegex (mkRegex "\d+") "abc 123 @#$" of
Nothing -> putStrLn "not ok"
Just _ -> putStrLn "ok"

java

Pattern pattern = Pattern.compile("\\d+");
Matcher matcher = pattern.matcher(text);
if (matcher.find()) {
System.out.println("ok");
}

ocaml

#load "str.cma" ;;

let re = Str.regexp "[0-9]+" in
try let _ = Str.search_forward re "abc 123 @#$" 0 in
print_string "ok"
with _ -> ()

perl

print "ok" if ("abc 123 @#\$" =~ m/\d+/)

php

if (preg_match("/\d+/", "abc 123 @#$"))
echo "ok";

python

found = re.search(r'\d+', 'abc 123 @#$')
if found:
print 'ok'

ruby

puts "ok" if (text=~/\d+/)

scala

if (Pattern.compile("\\d+").matcher("abc 123 @#$").find) println("ok")

Loop through a string matching a regex and performing an action for each match

Create a list [fish1,cow3,boat4] when matching "(fish):1 sausage (cow):3 tree (boat):4" with regex /$(\w+)$:(\d+)/

clojure

(let [matcher (re-matcher #"$(\w+)$:(\d+)" "(fish):1 sausage (cow):3 tree (boat):4")]
(loop [match (re-find matcher)
lst []]
(if match
(recur (re-find matcher) (conj lst (str (second match) (nth match 2))))
lst)))

cpp

Match^ match = Regex::Match("(fish):1 sausage (cow):3 tree (boat):4", "\$(\\w+)\$:(\\d+)");

while (match->Success)
{
list->Add(match->Groups[1]->Captures[0]->ToString() + match->Groups[2]->Captures[0]->ToString());
match = match->NextMatch();
}

erlang

solve(S) ->
R = "\$(\\w+?)\$:(\\d+)",
{match, M} = re:run(S,R, [global, {capture, all_but_first, list}]),
[ A++N || [A, N] <- M].

fantom

m := Regex<|$(\w+)$:(\d+)|>.matcher(s)
list := Str[,]
while (m.find) { list.add("${m.group(1)}${m.group(2)}") }

fsharp

let list = new ResizeArray<string>()
let mutable regmatch = (Regex.Match("(fish):1 sausage (cow):3 tree (boat):4", "\$(\\w+)\$:(\\d+)"))

while regmatch.Success do
list.Add(regmatch.Groups.[1].Captures.[0].ToString() ^ regmatch.Groups.[2].Captures.[0].ToString())
regmatch <- regmatch.NextMatch()
done

for word in list do printfn "%s" word done

// A solution without mutation:
let results =
Regex.Matches("(fish):1 sausage (cow):3 tree (boat):4", "\$(\\w+)\$:(\\d+)")
|> Seq.cast
|> Seq.map (fun (regmatch: Match) ->
regmatch.Groups.[1].Captures.[0].ToString() + regmatch.Groups.[2].Captures.[0].ToString()
)
|> List.ofSeq

groovy

list = (text =~ /$(\w+)$:(\d+)/).collect{ it[1] + it[2] }

list = []
text.eachMatch(/$(\w+)$:(\d+)/){
list << it[1] + it[2]
}

list = []
text.eachMatch(/$(\w+)$:(\d+)/){ m, name, number ->
list << "$name$number"
}

list = (text =~ /$(\w+)$:(\d+)/).collect{ all, name, num -> "$name$num" }

list = text.findAll(regex){ _, name, num -> "$name$num" }

list = text.findAll(regex){ it[1] + it[2] }

haskell

import Text.Regex

getParenNum s = case matchRegexAll re s of
Nothing -> []
Just (_,_,after,[word,num]) -> (word ++ num):getParenNum after where
re = mkRegex "\$(\\w+)\$:([[:digit:]]+)"

main = putStrLn (show (getParenNum "(fish):1 sausage (cow):3 tree (boat):4"))

java

List list = new ArrayList();
Pattern pattern = Pattern.compile("\$(\\w+)\$:(\\d+)");
Matcher matcher = pattern.matcher(text);
while(matcher.find()) {
list.add(matcher.group(1)+matcher.group(2));
}

ocaml

let result =
let str = "(fish):1 sausage (cow):3 tree (boat):4" in
let ms = Pcre.exec_all ~pat:"\$(\\w+)\$:(\\d+)" str in
Array.to_list (
Array.map (fun m ->
let s = Pcre.get_substrings m in
Printf.sprintf "%s%s" s.(1) s.(2);
) ms
)

perl

while ($text =~ /$(\w+)$:(\d+)/g) {
push @list, "$1$2"
}

php

preg_match_all("/$(\w+)$:(\d+)/", "(fish):1 sausage (cow):3 tree (boat):4", $matches);
for ($i=0, $c=count($matches[0]); $i < $c; $i++) {
$list[] = $matches[1][$i].$matches[2][$i];
}

python

map(''.join, re.findall(r"$(\w+)$:(\d+)", "(fish):1 sausage (cow):3 tree (boat):4"))
--------------------------------------------------------------------------
(''.join(m.groups()) for m in re.finditer(r"$(\w+)$:(\d+)", "(fish):1 sausage (cow):3 tree (boat):4"))

ruby

list = text.scan(/$(\w+)$:(\d+)/).collect{|x| x.join}

list=[]
text.scan(/$(\w+)$:(\d+)/) {
list << $1+$2
}

scala

val m = Pattern.compile("\$(\\w+)\$:(\\d+)").matcher("(fish):1 sausage (cow):3 tree (boat):4")
var list : List[String] = Nil

while (m.find) list = (m.group(1) + m.group(2)) :: list ; list = list.reverse

Replacing

Replace the first regex match in a string with a static string

Transform "Red Green Blue" into "R*d Green Blue" by replacing /e/ with "*"

clojure

(.replaceFirst (re-matcher #"e" "Red Green Blue") "*")

cpp

String^ Replaced = (gcnew Regex("e"))->Replace("Red Green Blue", "*", 1);

erlang

{ok, Replaced, _} = regexp:sub("Red Green Blue", "e", "*"),

re:replace("Red Green Blue", "e", "*", [{return, list}]).

fantom

replaced := Regex<|e|>.split("Red Green Blue",2).join("*")

fsharp

let replaced = ((new Regex("e")).Replace("Red Green Blue", "*", 1))
printfn "%s" replaced

groovy

replaced = "Red Green Blue".replaceFirst("e", "*")

java

String replaced = "Red Green Blue".replaceFirst("e", "*");

ocaml

let replaced = Str.replace_first (Str.regexp "e") "*" "Red Green Blue" in
print_endline replaced ;;

perl

$text =~s/e/*/;

php

echo preg_replace('/e/', '*', "Red Green Blue", 1);

python

print re.sub(r'e', '*', 'Red Green Blue', 1)

ruby

p "Red Green Blue".sub(/e/,'*')

scala

val replaced = "Red Green Blue".replaceFirst("e", "*")

Replace all regex matches in a string with a static string

Transform "She sells sea shells" into "She X X shells" by replacing /se\w+/ with "X"

clojure

(.replaceAll (re-matcher #"se\w+" "She sells sea shells") "X")

cpp

String^ Replaced = (gcnew Regex("se\\w+"))->Replace("She sells sea shells", "X");

String^ Replaced = Regex::Replace("She sells sea shells", "se\\w+", "X");

erlang

% Erlang uses 'egrep'-compatible regular expressions, so shortcuts like '\w' not supported
{ok, Replaced, _} = regexp:gsub("She sells sea shells", "se[A-Za-z0-9_]+", "X"),

re:replace("She sells sea shells", "se\\w+", "X", [global, {return, list}]).

fantom

replaced := Regex<|se\w+|>.split("She sells sea shells").join("X")

fsharp

let replaced = ((new Regex("se\\w+")).Replace("She sells sea shells", "X"))
printfn "%s" replaced

groovy

replaced = text.replaceAll(/se\w+/,"X")

java

String replaced = text.replaceAll("se\\w+", "X");

ocaml

let s = "She sells sea shells" in
Str.global_replace (Str.regexp "se[^ \\t\\n]*") "X" s

perl

$text = "She sells sea shells";
$text =~ s/se\w+/X/g;

php

echo preg_replace('/se\w+/', 'X', 'She sells sea shells');

python

transformed = re.sub(r'se\w+', 'X', 'She sells sea shells')

ruby

replaced = text.gsub(/se\w+/,"X")

scala

val replaced = "She sells sea shells".replaceAll("se\\w+", "X")

Replace all regex matches in a string with a dynamic string

Transform "The {Quick} Brown {Fox}" into "The kciuQ Brown xoF" by reversing words in braces using the regex /\{(\w+)\}/.

clojure

(def *string* "The {Quick} Brown {Fox}")
(def *regex* (re-pattern #"\{(\w+)\}"))

(println
(loop [result ""
src *string*
replace-strs (re-seq *regex* *string*)]
(if (empty? src)
result
(let [[match replacement] (first replace-strs)]
(if (= (first src) (first match))
; At the beginning of a sequence that should be replaced.
; Do replacement of a single match
(recur (str result (apply str (reverse replacement)))
(drop (count match) src)
(rest replace-strs))
; else, just copy one char from the source to the result
(recur (str result (first src))
(rest src)
replace-strs))))))

(clojure.string/replace "The {Quick} Brown {Fox}"
#"\{(\w+)\}"
(fn [[_ word]] (apply str (reverse word))))

cpp

String^ Replaced = (gcnew Regex("{(\\w+)}"))->Replace("The {Quick} Brown {Fox}", gcnew MatchEvaluator(&RegRep::RepGroup));

String^ Replaced = Regex::Replace("The {Quick} Brown {Fox}", "{(\\w+)}", gcnew MatchEvaluator(&RegRep::RepGroup));

erlang

% Erlang regular expressions lack both group capture and backreferences, thus this problem is not directly
% solvable. Presented solution is close, but not on-spec

String = "The {Quick} Brown {Fox}",
{match, FieldList} = regexp:matches(String, "\{([A-Za-z0-9_]+)\}"),

NewString = lists:foldl(fun ({Start, Length}, S) -> replstr(S, lists:reverse(string:substr(S, Start, Length)), Start) end, String, FieldList),

fantom

s := "The {Quick} Brown {Fox}"
m := Regex<|\{(\w+)\}|>.matcher(s)
buf := StrBuf(s.size)
last := 0
while (m.find)
{
buf.add(s[last..m.start-1]).add(m.group(1).reverse)
last = m.end
}
buf.add(s[last..-1])
replaced := buf.toStr

fsharp

open System
open System.Text.RegularExpressions
let reverseMatch (m:Match) =
String(m.Groups.[1].Value.ToCharArray() |> Array.rev)
let output = Regex.Replace("The {Quick} Brown {Fox}", @"\{(\w+)\}", reverseMatch)

groovy

replaced = "The {Quick} Brown {Fox}".replaceAll(/\{(\w+)\}/, { full, word -> word.reverse() } )

java

Matcher m = Pattern.compile("\\{(\\w+)\\}").matcher("The {Quick} Brown {Fox}");
StringBuffer sb = new StringBuffer(32), rsb = new StringBuffer(8);

while (m.find())
{
rsb.replace(0, rsb.length(), m.group(1)); rsb.reverse(); m.appendReplacement(sb, rsb.toString());
}
m.appendTail(sb);

ocaml

let s = "The {Quick} Brown {Fox}" in
let r = Str.regexp "{\$[^ \\t\\n]*\$}" in
Str.global_substitute r (fun m -> string_rev (Str.matched_group 1 m)) s

perl

$text = "The {Quick} Brown {Fox}";
$text =~ s/\{(\w+)\}/reverse($1)/ge;

php

// We have to use the e-modifier
preg_replace("/\{(\w+)\}/e", "''.strrev('\\1').''", "The {Quick} Brown {Fox}");

python

transformed = re.sub(r'\{(\w+)\}',
lambda match: match.group(1)[::-1],
'The {Quick} Brown {Fox}')

ruby

"The {Quick} Brown {Fox}".gsub(/\{(\w+)\}/) {|s| s[1..-2].reverse }

scala

val m = Pattern.compile("\\{(\\w+)\\}").matcher("The {Quick} Brown {Fox}")
val sb = new StringBuffer(32) ; val rsb = new StringBuffer(8)

while (m.find) { rsb.replace(0, rsb.length, m.group(1)) ; m.appendReplacement(sb, rsb.reverse.toString) }
m.appendTail(sb)