Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Substitution
Processing...

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?<!!)\\[(?=[^\\]]*[a-z])([a-zA-Z_]+[\\w]+)\\]"; final String string = "<?php\n" + "$options[$list[_capture_me]][]=array($list[_captureme],$list[_capture_me]);\n" + " $option_names[$list[_capture_me]]=$list[_captureme];\n" + " $product_name=$list[capture_me];\n" + "$product_name=$list[0];\n" + "$product_name=$list[DONTCAPTUREME];\n" + "$product_name=$list[CapTureMe];\n" + "$product_name=$list[CapTurEME];\n" + " $actionKey = $get[DONT_CAPTURE_ME];\n\n" + " if(array_key_exists(DONT_CAPTURE_ME,$get)) {\n" + " $actionKey = $get[DONT_CAPTURE_ME];\n" + " if(array_key_exists($actionKey,$this->arrPageActions)){\n" + " $this->arrAllTemplatesAndAttributes[$templateID][captureme]['Capture_Me'][$res[option_values_id]] = $res[DONT_CAPTURE_ME];\n" + "$old_faq_id.=\"$result[faq_id]&\"; \n" + " $result['toc']=\"<b><a href=$PHP_SELF#$result[faq_id]>$result['question']</a></b>\";}\n" + " $result['toc']=\"<b><a href=$PHP_SELF#$result[faq_id]>$result[QUESTION]</a></b>\";}\n" + "$login_groups_id = $check_admin[login_groups_id];\n" + "?>\n\n" + "<!--[if lt IE 7]> <html class=\"no-js lt-ie9 lt-ie8 lt-ie7\"> <![endif]-->\n\n" + "function check_input(field_name, field_size, message) {\n" + " if ($elements[capture_me] && (form.elements[dont_capture].type != \"hidden\") && $form.elements[capture_me]) {\n" + " var field_value = form.elements[dontcapure].value;\n" + " var field_value = $form.elements[capureme].value;\n\n" + " if (field_value == '' || field_value.length < field_size) {\n" + " error_message = error_message + \"* \" + message + \"\\n\";\n" + " error = true;\n" + " }\n" + " }\n" + "}"; final String subst = "['\\1']"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html