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

Substitution

Processing...

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"([^. >""])([ ])?([-])?(<\/p>)\n.*?>"; string substitution = @"$1$2"; string input = @"<p class=""calibre1"">pelled itself, riderless, in an endless orbit. </p> <p class=""calibre1"">The generator complex on the far side of this battlefield was </p> <p class=""calibre1"">intact, however. Reinforced concrete bunkers bristling with ma-</p> <p class=""calibre1"">chine guns surrounded a low building. The generators were deep </p> <p class=""calibre1"">beneath there. So far it looked as if the Covenant had not man-</p> <p class=""calibre1"">aged to take them, though not for lack of trying. </p> <p class=""calibre1"">""Contacts ahead,"" Joshua whispered. </p> <p class=""calibre1"">Four blips appeared on his motion sensor. Friend-or-foe tags </p> <p class=""calibre1"">identified them as UNSC Marines, Company Charlie. Serial </p> <p class=""calibre1"">numbers flashed next to the men as his HUD picked them out on a </p> <p class=""calibre1"">topo map of the area. </p> <p class=""calibre1"">Joshua handed Fred his sniper rifle, and he sighted the con-</p> <p class=""calibre1"">tacts through the scope. They were Marines, sure enough. They </p> <p class=""calibre1"">picked through the bodies that littered the area, looking for sur-</p> <p class=""calibre1"">vivors and policing weapons and ammo. </p> <p class=""calibre1"">Fred frowned; something about the way the Marine squad </p> <p class=""calibre1"">moved didn't feel right. They lacked unit cohesion, with their </p> <p class=""calibre1"">firstd, <i class=""calibre4"">you may as well drop with good intel. </i> </p> <p class=""calibre1"">Captain Keyes frowned on the ship's viewscreen, a </p> <p class=""calibre1"">""Roger that,"" he replied, ""though I think I've had enough surprises for one op."" </p> <p class=""calibre1"">Kelly chuckled. </p>"; Regex regex = new Regex(pattern); string result = regex.Replace(input, substitution); } }

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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx