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 = "\"\""; $result = preg_replace($re, $subst, $str); echo "The result of the substitution is ".$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 PHP, please visit: http://php.net/manual/en/ref.pcre.php