Regular Expressions 101

Save & Share

  • Regex Version: ver. 4
  • 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

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 = "(^[\\s]*[-+]?[0-9]*?\\.?[0-9]+([eE][-+]?[0-9]+)?[\\s]*$|^[\\s]*[-+]?[0-9]+\\.?[\\s]*$)"; final String string = "0\n" + "0.\n" + "0.0\n" + "0.00\n" + "0.0e0\n" + "0.0e-0\n" + "0.0e+0 \n" + "+0 \n" + "+0. \n" + "+0.0\n" + "+0.00\n" + "+0.0e0\n" + "+0.0e-0\n" + "+0.0e+0\n" + "-0 \n" + "-0.\n" + "-0.0\n" + "-0.00\n" + "-0.0e0\n" + "-0.0e-0\n" + "-0.0e+0\n" + "1.\n" + "2.\n" + "3.\n" + "4.\n" + "-1.\n" + "-2.\n" + "-3.\n" + "-4.\n" + ".1\n" + ".2\n" + ".3\n" + ".4\n" + "-.1\n" + "-.2\n" + "-.3\n" + "-.4\n" + "1.0\n" + "3.0\n" + "4.0\n" + "5.0\n" + "-1.0\n" + "-2.0\n" + "-3.0\n" + "-4.0\n" + "-5.0\n" + "5.0123456\n" + "-5.012345678\n" + "-1\n" + "10\n" + "-10\n" + "10.0\n" + "-10.0\n" + "-10.01234\n" + "10.01234\n" + "0\n" + "1\n" + "01\n" + "001\n" + " 1 \n\n" + "Ne doit pas être validé\n\n" + ".\n" + "1..\n" + ".1.\n" + "..1\n" + "toto\n" + "1a\n" + "a1\n" + "a1a\n" + "1 a\n" + "a 1\n" + "a 1 a\n" + "-.1.\n" + "+.1."; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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