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 = /(\b\S+\b)(?=.*\b\1\b)/m str = '123-1 123-2 test-1 test-1 w/e 10/04/20 Company w/e 09/06/20 083020-090620 a/b 01/01 test_1 test_2 a/b a/b Inv 50049 50049 Inv 50195 PrjPAN02 Inv 51360-1, 51366-7; 51372 Inv 51360-1, 51366-7; 372 PrjPAN02 Inv 51360-1, 51366-7; 51372 51372 Inv 513601, 51366-7; 372 PrjPAN02 55009, 55017, 55022 55001, 55022, 55025 55254, 61 55246,66,69 55733, 41, 44 55727, 45,48 57269, 71,74,75, 57354 57266, 73 57437, 38, 41, 43 57434, 40 w/e 09/20/20 091320-092020' 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