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

r"
"
gm

Test String

Code Generator

Language

Generated Code

re = /\b\d+\s+[A-Z]{3}\s+[A-Z0-9]+/m str = ' 1 -1 2 SER HA H 4.477 0.003 1 2 -1 2 SER HB2 H 3.765 0.001 1 3 -1 2 SER HB3 H 3.765 0.001 1 4 -1 2 SER C C 173.726 0.2 1 5 -1 2 SER CA C 58.16 0.047 1 6 -1 2 SER CB C 64.056 0.046 1 7 0 3 HIS H H 8.357 0.004 1 8 0 3 HIS HA H 4.725 0.003 1 9 0 3 HIS HB2 H 3.203 0.003 2 ..... 63 7 10 GLU HA H 4.328 0.004 1 64 7 10 GLU HB2 H 2.154 0.005 2 65 7 10 GLU HB3 H 2.156 0.004 2 66 7 10 GLU HG2 H 2.262 0.014 2 67 7 10 GLU HG3 H 2.464 0.001 2 68 7 10 GLU C C 177.242 0.2 1 69 7 10 GLU CA C 59.009 0.068 1' # Print the match result str.scan(re) do |match| puts match.to_s end

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