Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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

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 = " - \\d+ : (.+)"; final String string = " - 0 : <NSLayoutConstraint:0x6000035b77a0 UILayoutGuide:0x600002fe0e00''.centerY == UIFoundation.TitleSubtitleView:0x7f909a93c110.centerY (active)>\n" + " - 1 : <NSLayoutConstraint:0x6000035b7750 H:|-(0)-[UILayoutGuide:0x600002fe0e00''] (active, names: '|':UIFoundation.TitleSubtitleView:0x7f909a93c110 )>\n" + " - 2 : <NSLayoutConstraint:0x6000035b77f0 UILayoutGuide:0x600002fe0e00''.trailing == UIFoundation.TitleSubtitleView:0x7f909a93c110.trailing (active)>\n" + " - 3 : <NSLayoutConstraint:0x6000035b7840 V:|-(>=0)-[UILayoutGuide:0x600002fe0e00''] (active, names: '|':UIFoundation.TitleSubtitleView:0x7f909a93c110 )>\n" + " - 4 : <NSLayoutConstraint:0x6000035b7890 V:|-(0@250)-[UILayoutGuide:0x600002fe0e00''] priority:250 (active, names: '|':UIFoundation.TitleSubtitleView:0x7f909a93c110 )>\n" + " - 5 : <NSLayoutConstraint:0x6000035b78e0 UILayoutGuide:0x600002fe0ee0''.top == UILayoutGuide:0x600002fe0e00''.top + 12 (active)>\n" + " - 6 : <NSLayoutConstraint:0x6000035b7930 UILayoutGuide:0x600002fe0ee0''.bottom == UILayoutGuide:0x600002fe0e00''.bottom - 12 (active)>\n" + " - 7 : <NSLayoutConstraint:0x6000035b7980 UILayoutGuide:0x600002fe0ee0''.leading == UILayoutGuide:0x600002fe0e00''.leading + 16 (active)>\n" + " - 8 : <NSLayoutConstraint:0x6000035b79d0 UILayoutGuide:0x600002fe0ee0''.trailing == UILayoutGuide:0x600002fe0e00''.trailing - 16 (active)>\n" + " - 9 : <NSLayoutConstraint:0x6000035b7a70 UIFoundation.FadingLabel:0x7f909a9334e0.top == UILayoutGuide:0x600002fe0ee0''.top (active)>\n" + " - 10 : <NSLayoutConstraint:0x6000035b7b10 UIFoundation.FadingLabel:0x7f909a9334e0.leading == UILayoutGuide:0x600002fe0ee0''.leading (active)>\n" + " - 11 : <NSLayoutConstraint:0x6000035b7b60 UIFoundation.FadingLabel:0x7f909a9334e0.trailing == UILayoutGuide:0x600002fe0ee0''.trailing (active)>\n" + " - 12 : <NSLayoutConstraint:0x6000035b7a20 V:[UIFoundation.FadingLabel:0x7f909a9334e0]-(8)-[UIFoundation.FadingLabel:0x7f909a81b610] (active)>\n" + " - 13 : <NSLayoutConstraint:0x6000035b7c00 UIFoundation.FadingLabel:0x7f909a81b610.leading == UILayoutGuide:0x600002fe0ee0''.leading (active)>\n" + " - 14 : <NSLayoutConstraint:0x6000035b7c50 UIFoundation.FadingLabel:0x7f909a81b610.trailing == UILayoutGuide:0x600002fe0ee0''.trailing (active)>\n" + " - 15 : <NSLayoutConstraint:0x6000035b7ca0 UIFoundation.FadingLabel:0x7f909a9334e0.bottom <= UILayoutGuide:0x600002fe0ee0''.bottom (active)>\n" + " - 16 : <NSLayoutConstraint:0x6000035b7ac0 UIFoundation.FadingLabel:0x7f909a9334e0.bottom == UILayoutGuide:0x600002fe0ee0''.bottom (active)>"; 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