Regular Expressions 101

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Function

  • Match
  • Substitution
  • List
  • Unit Tests (6)

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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 \b(?!\S*cat)([a-z])*\b assert that regex does not match
given the string cushufhuc cat jciaicat dnjd cat assert that capture group регулярное выражение empty string
given the string fddfh9jidicjdi icat jjisjijidjicuiharjji… assert that capture group регулярное выражение empty string
given the string cat poshel dosdo darcat ddfkoscdacatfdmk… assert that regex does match
given the string fdfggeo cat dkdkfo catkfogk cktkdocatfg… assert that regex does match
given the string fdf rejijf cat jsijdjirkjfdirkfdjkg assert that regex does match