Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

Generated Code

import re regex = re.compile((r'class MyNewLanguage extends PureComponent {\n\n' r' //\n' r' // Proptypes\n\n' r' static propTypes = {\n' r' regex: PropTypes.string.isRequired,\n' r' flags: PropTypes.string.isRequired,\n' r' delimiter: PropTypes.string.isRequired,\n' r' testString: PropTypes.string.isRequired,\n' r' isSubstituting: PropTypes.bool.isRequired,\n' r' isGlobal: PropTypes.bool.isRequired,\n' r' substString: PropTypes.string\n' r' };\n\n' r' //\n' r' // Control\n\n' r' // If you need to manipulate any data, you should preferably do it in a function defined \n' r' // on the class body here. This could for example be sanitizing data (escaping quotes, etc).\n\n' r' //\n' r' // Render functions\n\n' r' render() {\n' r' return (\n' r' <Highlight lang="myNewLanguage">\n' r' {this._renderCode()}\n' r' </Highlight>\n' r' );\n' r' }\n\n' r' _renderCode() {\n' r' const { regex, flags, delimiter, testString, isSubstituting, substString, isGlobal } = this.props;\n\n' r' const codeString = new CodeString();\n' r' \n' r' // CodeString is a basic class that allows you to create a code snippet without having\n' r' // to worry about indentation or newlines.\n\n' r' // The only functions are `append`, `indent` and `toString`.\n' r' // The implementation can be found on this page.\n\n' r' // Create your code string here\n' r' codeString.append(`Use string literals when ${regex} interpolating ${flags} data`);\n' r' \n' r' return codeString.toString();\n' r' }\n\n' r'}\n\n' r'export default MyNewLangauge;'), flags=re.MULTILINE) test_str = ("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") subst = "/You have bound GoPlus Security Sentinel. Bound address: 0x8baa0e5a9f879ef40d55b7da808d94aca314742c/gm" result = regex.sub(subst, test_str) if result: print(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 Python, please visit: https://docs.python.org/3/library/re.html