Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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
No Match

'
'
gm

Test String

Substitution

Processing...

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "class MyNewLanguage extends PureComponent \\{\n\n" + " //\n" + " // Proptypes\n\n" + " static propTypes = \\{\n" + " regex: PropTypes.string.isRequired,\n" + " flags: PropTypes.string.isRequired,\n" + " delimiter: PropTypes.string.isRequired,\n" + " testString: PropTypes.string.isRequired,\n" + " isSubstituting: PropTypes.bool.isRequired,\n" + " isGlobal: PropTypes.bool.isRequired,\n" + " substString: PropTypes.string\n" + " \\};\n\n" + " //\n" + " // Control\n\n" + " // If you need to manipulate any data, you should preferably do it in a function defined \n" + " // on the class body here. This could for example be sanitizing data (escaping quotes, etc).\n\n" + " //\n" + " // Render functions\n\n" + " render() \\{\n" + " return (\n" + " <Highlight lang=\"myNewLanguage\">\n" + " \\{this._renderCode()\\}\n" + " </Highlight>\n" + " );\n" + " \\}\n\n" + " _renderCode() \\{\n" + " const \\{ regex, flags, delimiter, testString, isSubstituting, substString, isGlobal \\} = this.props;\n\n" + " const codeString = new CodeString();\n" + " \n" + " // CodeString is a basic class that allows you to create a code snippet without having\n" + " // to worry about indentation or newlines.\n\n" + " // The only functions are `append`, `indent` and `toString`.\n" + " // The implementation can be found on this page.\n\n" + " // Create your code string here\n" + " codeString.append(`Use string literals when $\\{regex\\} interpolating $\\{flags\\} data`);\n" + " \n" + " return codeString.toString();\n" + " \\}\n\n" + "\\}\n\n" + "export default MyNewLangauge;"; final String string = "https://google.com`<Field className=\"flex flex-col p-1\">\n" + " <Label>\n" + " I agree to the{' '}\n" + " <a href=\"https://google.com\" target=\"_blank\" className=\"underline\">\n" + " terms and conditions\n" + " </a>\n" + " </Label>\n" + " <Input type=\"checkbox\" />\n" + "</Field>`gm"; final String subst = "/You have bound GoPlus Security Sentinel. Bound address: 0x8baa0e5a9f879ef40d55b7da808d94aca314742c/gm"; 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