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

`
`
g

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(src="cid:).*?(.+?(\.gif|\.png|\.jpg))+?([^"]*)`) var str = `bodyHtmlText: <p class=MsoNormal><a href="http://www.centric.eu/craft"><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;text-decoration:none'><img border=0 width=300 height=100 id="_x0000_i1026" src="cid:image001.jpg@01D2E5DE.EC0337E0" alt="cid:image002.jpg@01D19BE7.F4CB9B70"></span></a><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p>&nbsp;</o:p></span></p><p class=MsoNormal><a href="https://www.facebook.com/Centric"><span style='color:blue;text-decoration:none'><img border=0 width=31 height=75 id="_x0000_i1027" src="cid:image002.jpg@01D2E5DE.EC0337E0" alt="Like ons"></span></a><span lang=EN-US style='color:#1F497D'>&nbsp; </span><a href="http://www.linkedin.com/company/centric"><span style='color:blue;text-decoration:none'> USAGE: const string patternImageFilesInBody = @"(src=""cid:).*?(.+?(\.gif|\.png|\.jpg))+?([^""]*)"; //const string patternImageFilesInBody = @"(src=""cid:).*?/?([^/]+?(\.gif|\.png|\.jpg))+?(@[^""]*)"; //const string patternImageFilesInBody = @"(src=\""cid:).*?/?([^/]+?(\.gif|\.png|\.jpg))+?(@.................)"; var bodyIndependentsoft = Regex.Replace(bodyHtmlText, patternImageFilesInBody, m => "src=\"" + tempFolder + "/" + m.Groups[2].Value + "\""); ` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", i) } }

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 Golang, please visit: https://golang.org/pkg/regexp/