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

r"
"
gmi

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

use strict; my $str = '// diagGetParameterRaw(transition_1_2_0_Resp, "SecurityClass", buffer, 4096); // _DiagGenerateKeyFromSeed (buffer, 1, 0x11, "BR120x", "", op1, 6, _length); length = 6; ******* diagGetParameterRaw(transition_1_2_0_Resp, "SecurityClass", buffer, 4096); _DiagGenerateKeyFromSeed (buffer, 1, 0x11, "BR120x", "", op1, 6, _length); length = 6; diagGetParameterRaw(transition_1_2_0_Resp, "SecurityClass", buffer, 4096); _DiagGenerateKeyFromSeed (buffer, 1, 0x11, "BR120x", "", op1, 6, _length); length = 6; **************** RawDiagGetParameterRaw(transition_1_0_0_Resp, 16, 64, buffer, 4096); _DiagGenerateKeyFromSeed (buffer, 8, 0x11, "BR120x", "", op1, 6, _length); length = 6; '; my $regex = qr/(?P<first>^(?P<intend>\s*?)diagGetParameterRaw.+?(?P<diagresp>\w.+?),.*?\"SecurityClass\", (?P<first_rest>.+?;(?P<newline>[\n\r]+)))(?P<second>(?P<second_start>\s*?_DiagGenerateKeyFromSeed.+.?buffer,).+?(?P<second_rest>0x\d+?,.+))/mip; my $subst = '\\g<newline>\\g<intend>\\g<newline>//\\g<intend>removed the next two lines as diva uses only one of our three parameters\\g<newline>//\\g<first>//\\g<second>\\g<newline>//\\g<intend>\\g<newline>//\\g<intend>this works correctly:\\g<newline>\\g<intend>\\g<newline>\\g<intend>RawDiagGetParameterRaw ( \\g<diagresp>, 16, 64, \\g<first_rest>\\g<second_start> 8, \\g<second_rest>\\g<newline>\\g<newline>//\\g<intend>replacement ends here\\g<newline>\\g<intend>'; my $result = $str =~ s/$regex/$subst/rg; print "The result of the substitution is' $result\n";

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 Perl, please visit: http://perldoc.perl.org/perlre.html