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 = '/([{,]([A-z0-9 ]+?)[,][A-z0-9, ]*?)\2+([,}])/m'; $str = '\\cite{Duran2016TIE,Vu2019ICIT,Ryu2006TIA,Zhao1996TECa,Zhao1996TECb,Guzman2012EPE,Guzman2016TIE,Duran2016TIE,Vu2019ICIT,Chen2020TIE,Chen2020Access,Priestley2020TIE,Fan2020TVT,Vu2019ICIT,Bermudez2018TPEL,Chikondra2021TIE,Che2014TPEL,Bermudez2018TPEL,Vu2019ICIT,Liu2018TPEL,Tian2018TIA,Liu2018TPEL,Liang2018Access,Vu2022TPEL,Tian2017TPEL,Tani2012TPEL,Priestley2020TIE,Fnaiech2010TIE,Betin2012TIE,Zhao1996TECa,Zhao1996TECb,Geng2019Access,Wang2017TIE,Lu2017TIA,Lu2018IET,Lu2019TIE,Liang2020Access,Souza2018TIA,Souza2020TIA,Vu2022TPEL,Zhou2016TEC,Bermudez2017TIE,Chikondra2021TIE,Zhou2021TIE,Huang2020TIE,Zhou2020TPEL,Huang2020TPEL,Guzman2012EPE,Guzman2014TIE,Guzman2016TIE,Prieto2018TIE,Liu2020TPELb,Huang2018JESTPE,Tao2020TPEL,Tao2021TPEL,Priestley2020TIE,Ryu2006TIA,Wang2018TIA,Khadar2019MMC,Chen2020Access,Chen2020TIE,Xiong2020TIE,Hu2021JESTPE,Tian2021TEC,Tian2017TPEL,Cheng2018TPEL,Zhou2017TIE,Tian2017TPELb,Tian2021TIE,Tian2018TIA,Liu2018TPEL,Tian2021TIEb,Chen2019TIE,Liang2018Access,Xu2019TIE,Bermudez2018TPEL,Vu2019ICIT,Fan2020TVT,Duran2016TIE,Vu2019ICIT}'; $subst = "$1$3"; $result = preg_replace($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