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 (62)

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
An explanation of your regex will be automatically generated as you type.
  • 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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/

Unit Tests

given the string 123456789012.1234 assert that regex does not match
given the string 123456789012 assert that regex does not match
given the string 12345678901.1234 assert that regex does match
given the string 1.03a2 assert that regex does not match
given the string -0.123 assert that regex does not match
given the string -.143 assert that regex does not match
given the string -124 assert that regex does not match
given the string -4 assert that regex does not match
given the string 5.1.2 assert that regex does not match
given the string 5. assert that regex does not match
given the string 1. assert that regex does not match
given the string 0. assert that regex does not match
given the string 1.00012 assert that regex does not match
given the string 124124.124124124124124124 assert that regex does not match
given the string 0.001000 assert that regex does not match
given the string 0.10000 assert that regex does not match
given the string 0.00001 assert that regex does not match
given the string .00000 assert that regex does not match
given the string .0000 assert that regex does not match
given the string .000 assert that regex does not match
given the string .00 assert that regex does not match
given the string .0 assert that regex does not match
given the string 0.00000 assert that regex does not match
given the string 0.0000 assert that regex does not match
given the string 0.000 assert that regex does not match
given the string 0.00 assert that regex does not match
given the string 0.0 assert that regex does not match
given the string 0 assert that regex does not match
given the string 1.0000 assert that regex does match
given the string 1.000 assert that regex does match
given the string 1.00 assert that regex does match
given the string 1.0 assert that regex does match
given the string 1234.1234 assert that regex does match
given the string 1.12 assert that regex does match
given the string 1.123 assert that regex does match
given the string 1.1234 assert that regex does match
given the string 1.1 assert that regex does match
given the string 1.0100 assert that regex does match
given the string 1.1000 assert that regex does match
given the string 1.0100 assert that regex does match
given the string 1.001 assert that regex does match
given the string 1.0010 assert that regex does match
given the string 1.0001 assert that regex does match
given the string 1 assert that regex does match
given the string .123 assert that regex does match
given the string .1234 assert that regex does match
given the string .1 assert that regex does match
given the string .0100 assert that regex does match
given the string .1000 assert that regex does match
given the string .010 assert that regex does match
given the string .001 assert that regex does match
given the string .0010 assert that regex does match
given the string .0001 assert that regex does match
given the string 0.123 assert that regex does match
given the string 0.1234 assert that regex does match
given the string 0.1 assert that regex does match
given the string 0.0100 assert that regex does match
given the string 0.1000 assert that regex does match
given the string 0.010 assert that regex does match
given the string 0.001 assert that regex does match
given the string 0.0010 assert that regex does match
given the string 0.0001 assert that regex does match