Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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 = '/\d\d*[.]?\d*\d/m'; $str = '\\par }{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid13305240\\charrsid3175333 \\hich\\af1\\dbch\\af31505\\loch\\f1 Xray-source / Detector distance:}{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\uld\\insrsid13305240\\charrsid3175333 \\tab \\tab }{ \\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid13305240\\charrsid3175333 \\hich\\af1\\dbch\\af31505\\loch\\f1 529 mm}{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid13305240 \\hich\\af1\\dbch\\af31505\\loch\\f1 (20.861 inches) \\par \\hich\\af1\\dbch\\af31505\\loch\\f1 Rotation axis / Detector \\hich\\af1\\dbch\\af31505\\loch\\f1 distance:}{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\uld\\insrsid13305240 \\hich\\af1\\dbch\\af31505\\loch\\f1 \\tab }{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid13305240 \\hich\\af1\\dbch\\af31505\\loch\\f1 467.364 mm (18.4 inches) \\par }{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid13305240\\charrsid3175333 \\hich\\af1\\dbch\\af31505\\loch\\f1 Rotation axis / Xray-source distance:}{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\uld\\insrsid13305240\\charrsid3175333 \\hich\\af1\\dbch\\af31505\\loch\\f1 \\tab }{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid13305240\\charrsid3175333 \\hich\\af1\\dbch\\af31505\\loch\\f1 62.5 mm}{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid13305240 \\hich\\af1\\dbch\\af31505\\loch\\f1 \\par \\tab \\hich\\af1\\dbch\\af31505\\loch\\f1 type:}{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\uld\\insrsid3017018 \\tab \\tab \\tab }{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid3017018 \\hich\\af1\\dbch\\af31505\\loch\\f1 step \\par \\tab }{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid3017018\\charrsid7233753 \\hich\\af1\\dbch\\af31505\\loch\\f1 # projections:}{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\uld\\insrsid3017018\\charrsid7233753 \\tab \\tab }{\\rtlch\\fcs1 \\ab\\af1\\afs20 \\ltrch\\fcs0 \\b\\f1\\fs20\\insrsid3017018\\charrsid7233753 \\hich\\af1\\dbch\\af31505\\loch\\f1 1440 \\par }{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid3017018 \\tab \\hich\\af1\\dbch\\af31505\\loch\\f1 # frames averaged:}{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\uld\\insrsid3017018 \\tab }{\\rtlch\\fcs1 \\af1\\afs20 \\ltrch\\fcs0 \\f1\\fs20\\insrsid3017018'; $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