Regular Expressions 101

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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

re = /^\s*(?:(?:\S\s?)*\s+){2}| +(?= )/m str = ' 0 4D1F 8172 DC.L $4D1F8172 ; Rom CheckSum 4 0040 002A DC.L $0040002A ; Boot Vector = EBootStart 8 00 DC.B $00 ; Machine Type 9 75 DC.B $75 ; Rom Version A 6000 0056 Bra L3 E 6000 0750 Bra L62 12 6000 0044 Bra L2 16 6000 0016 Bra E_6 1A 0001 76F8 DC.L $000176F8 ; offset of Resources in ROM 1E 4EFA 2BFC Jmp P_mvDoEject 22 0000 0000 DC.L $00000000 26 0000 0000 DC.L $00000000 1FFE2 4B57 4B20 4C41 DC.B \'KWK LA\'' subst = '' result = str.gsub(re, subst) # Print the result of the substitution puts 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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html