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 (19)

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

/
/
gD

Unit Tests

given the string 1 assert that regex does match
given the string 11 assert that regex does match
given the string 0.0 assert that regex does match
given the string 111 assert that regex does match
given the string 1.0 assert that regex does match
given the string 1.1.1 assert that regex does match
given the string 12.12.12 assert that regex does match
given the string 5. assert that regex does not match
EMPTY
given the string 1..0.1 assert that regex does not match
given the string 12..12.12 assert that regex does not match
given the string 12.12..12 assert that regex does not match
given the string -12.-5.-12 assert that regex does not match
given the string 1..1 assert that regex does not match
given the string 1.hallo.5 assert that regex does not match
given the string .5 assert that regex does not match
given the string ... assert that regex does not match
given the string . assert that regex does not match
given the string a5 assert that regex does not match