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 = @"( \d{1,2})5(\d{2} )"; string substitution = @"\1:\2"; string input = @"part1.htm"">MiniTOC</a><a class=""toc1"" part2.htm"">2/5/18, 4549 PM part3.htm"">2/7/18, 4516 PM part4.htm"">2/15/18, 2557 PM part5.htm"">2/20/18, 2507 PM part6.htm"">2/21/18, 3502 PM part7.htm"">2/21/18, 5506 PM part8.htm"">2/22/18, 10503 AM part9.htm"">2/22/18, 1543 PM part10.htm"">2/27/18, 3514 PM part11.htm"">2/28/18, 2533 PM part12.htm"">3/1/18, 1515 PM part13.htm"">3/1/18, 2527 PM part14.htm"">3/1/18, 6547 PM part15.htm"">3/1/18, 8557 PM part16.htm"">3/4/18, 11540 AM part17.htm"">3/5/18, 4546 PM part18.htm"">3/6/18, 12548 PM part19.htm"">3/6/18, 2518 PM part20.htm"">3/7/18, 12535 PM part21.htm"">3/8/18, 8500 AM part22.htm"">3/8/18, 10521 AM part23.htm"">3/8/18, 12559 PM part24.htm"">3/9/18, 10540 AM part25.htm"">3/9/18, 1501 PM part26.htm"">3/9/18, 6514 PM part27.htm"">3/12/18, 8514 PM part28.htm"">3/14/18, 12520 PM part29.htm"">3/14/18, 2537 PM part30.htm"">3/15/18, 2514 PM part31.htm"">3/15/18, 3549 PM part32.htm"">3/21/18, 11506 AM part33.htm"">3/22/18, 2518 PM part34.htm"">3/22/18, 3523 PM part35.htm"">3/22/18, 4554 PM part36.htm"">3/26/18, 3543 PM part37.htm"">4/2/18, 1555 PM part38.htm"">4/2/18, 4532 PM part39.htm"">4/5/18, 1557 PM part40.htm"">4/6/18, 4536 PM part41.htm"">4/6/18, 5540 PM part42.htm"">4/6/18, 7501 PM part43.htm"">4/7/18, 5524 AM part44.htm"">4/16/18, 12525 PM part45.htm"">4/17/18, 4502 PM part46.htm"">4/23/18, 7520 PM part47.htm"">4/25/18, 3527 PM part48.htm"">4/25/18, 5513 PM part49.htm"">4/26/18, 2534 PM part50.htm"">4/26/18, 6513 PM part51.htm"">5/1/18, 3523 PM part52.htm"">5/3/18, 3540 PM part53.htm"">5/4/18, 12539 PM part54.htm"">5/8/18, 12539 PM part55.htm"">5/8/18, 2549 PM part56.htm"">5/9/18, 12506 PM part57.htm"">5/15/18, 3525 PM part58.htm"">5/23/18, 6545 PM part59.htm"">5/24/18, 2559 PM part60.htm"">5/24/18, 5523 PM part61.htm"">5/26/18, 3509 PM part62.htm"">5/27/18, 11519 AM part63.htm"">5/30/18, 4554 PM part64.htm"">5/26/18, 1507 PM part65.htm"">5/31/18, 2558 PM part66.htm"">6/7/18, 2546 PM part67.htm"">6/11/18, 7531 PM part68.htm"">6/12/18, 10547 AM part69.htm"">6/12/18, 3529 PM part70.htm"">6/13/18, 7536 PM part71.htm"">6/14/18, 3527 PM part72.htm"">6/19/18, 8507 AM part73.htm"">6/19/18, 3528 PM part74.htm"">6/19/18, 5519 PM part75.htm"">6/20/18, 10507 AM part76.htm"">6/21/18, 10545 AM part77.htm"">6/21/18, 12544 PM part78.htm"">6/21/18, 3534 PM part79.htm"">6/23/18, 11506 AM part80.htm"">6/23/18, 3505 PM part81.htm"">6/23/18, 6500 PM part82.htm"">6/24/18, 10535 AM part83.htm"">6/24/18, 12556 PM part84.htm"">6/25/18, 7517 PM part85.htm"">6/26/18, 3517 PM part86.htm"">6/26/18, 4559 PM part87.htm"">6/27/18, 9551 AM </a><a class=""toc1"" part88.htm"">6/27/18, 11532 AM part89.htm"">6/28/18, 4515 PM </a><a class=""toc1"" part90.htm"">7/2/18, 6529 PM part91.htm"">7/3/18, 3554 PM part92.htm"">7/3/18, 5545 PM part93.htm"">7/3/18, 7556 PM part94.htm"">7/3/18, 9503 PM part95.htm"">7/7/18, 5531 PM part96.htm"">7/9/18, 4553 PM part97.htm"">7/10/18, 8554 AM part98.htm"">7/10/18, 5516 PM part99.htm"">7/11/18, 11531 AM part100.htm"">7/11/18, 3550 PM part101.htm"">7/12/18, 4549 PM part102.htm"">7/15/18, 3524 PM part103.htm"">7/16/18, 10525 AM part104.htm"">7/16/18, 11534 AM part105.htm"">7/16/18, 6544 PM part106.htm"">7/18/18, 11505 AM part107.htm"">7/19/18, 1537 PM part108.htm"">7/19/18, 3532 PM part109.htm"">7/24/18, 10500 AM part110.htm"">7/24/18, 2514 PM part111.htm"">7/24/18, 3555 PM part112.htm"">7/24/18, 7506 PM part113.htm"">8/9/18, 12537 PM part114.htm"">8/13/18, 3531 PM part115.htm"">8/13/18, 5551 PM part116.htm"">8/14/18, 12509 PM part117.htm"">8/14/18, 1532 PM part118.htm"">8/14/18, 3539 PM part119.htm"">8/16/18, 4548 PM part120.htm"">8/16/18, 4548 PM part121.htm"">8/21/18, 6509 PM part122.htm"">8/23/18, 11557 AM part123.htm"">8/28/18, 4537 PM part124.htm"">8/30/18, 7528 PM part125.htm"">8/30/18, 10500 PM part126.htm"">9/4/18, 2538 PM part127.htm"">9/4/18, 5515 PM part128.htm"">9/5/18, 3538 PM part129.htm"">9/7/18, 5519 PM part130.htm"">9/10/18, 3518 PM part131.htm"">9/13/18, 8541 AM part132.htm"">9/13/18, 11512 AM part133.htm"">9/13/18, 12551 PM part134.htm"">9/17/18, 6502 PM part135.htm"">9/18/18, 3555 PM part136.htm"">9/19/18, 9506 PM part137.htm"">9/19/18, 11504 PM part138.htm"">9/20/18, 12531 PM part139.htm"">9/24/18, 4502 PM part140.htm"">9/24/18, 6518 PM part141.htm"">9/25/18, 9550 AM part142.htm"">9/25/18, 5512 PM part143.htm"">9/26/18, 12549 PM part144.htm"">9/26/18, 6533 PM part145.htm"">9/28/18, 9543 AM part146.htm"">10/1/18, 7558 AM part147.htm"">10/1/18, 3538 PM part148.htm"">10/3/18, 10551 AM part149.htm"">10/3/18, 3521 PM part150.htm"">10/3/18, 4528 PM part151.htm"">10/3/18, 5529 PM part152.htm"">10/8/18, 11521 AM part153.htm"">10/8/18, 2526 PM part154.htm"">10/8/18, 4538 PM part155.htm"">10/9/18, 1504 PM part156.htm"">10/9/18, 4529 PM part157.htm"">10/9/18, 6552 PM part158.htm"">10/10/18, 6509 PM part159.htm"">10/11/18, 1544 PM part160.htm"">10/11/18, 3527 PM part161.htm"">10/11/18, 5552 PM part162.htm"">10/11/18, 8500 PM part163.htm"">10/16/18, 2515 PM part164.htm"">10/16/18, 4501 PM part165.htm"">10/18/18, 10541 AM part166.htm"">10/18/18, 1505 PM part167.htm"">10/18/18, 4524 PM part168.htm"">10/18/18, 7537 PM part169.htm"">10/19/18, 11532 AM part170.htm"">10/22/18, 9539 AM part171.htm"">10/22/18, 10543 AM part172.htm"">10/22/18, 12514 PM part173.htm"">10/22/18, 2523 PM part174.htm"">10/24/18, 10506 AM part175.htm"">10/24/18, 12535 PM part176.htm"">10/24/18, 5558 PM part177.htm"">11/1/18, 3525 PM part178.htm"">11/1/18, 3525 PM part179.htm"">11/5/18, 11509 AM part180.htm"">11/5/18, 1544 PM part181.htm"">11/8/18, 6521 PM part182.htm"">11/9/18, 11538 AM part183.htm"">11/10/18, 11525 AM part184.htm"">11/10/18, 2531 PM part185.htm"">11/14/18, 10530 AM part186.htm"">11/14/18, 2505 PM part187.htm"">11/14/18, 4521 PM part188.htm"">11/14/18, 5527 PM part189.htm"">11/15/18, 11541 AM part190.htm"">11/15/18, 12558 PM part191.htm"">11/18/18, 8559 PM part192.htm"">11/19/18, 11502 AM part193.htm"">11/19/18, 12512 PM part194.htm"">11/26/18, 12537 PM part195.htm""> 11/27/18, 3535 PM part196.htm"">11/28/18, 9535 AM part197.htm"">11/28/18, 12551 PM part198.htm"">11/29/18, 11541 AM part199.htm"">12/3/18, 11512 AM part200.htm"">12/3/18, 4501 PM part201.htm"">12/4/18, 12510 PM part202.htm"">12/4/18, 2504 PM part203.htm"">12/4/18, 3559 PM part204.htm"">12/7/18, 11548 AM part205.htm"">12/7/18, 1542 PM part206.htm"">12/10/18, 12521 PM part207.htm"">12/11/18, 12518 PM part208.htm"">12/14/18, 9517 AM part209.htm"">12/14/18, 11554 AM part210.htm"">12/14/18, 1547 PM part211.htm"">12/14/18, 3530 PM part212.htm"">12/14/18, 9531 PM part213.htm"">12/16/18, 6506 PM part214.htm"">12/17/18, 11556 AM part215.htm"">12/19/18, 4500 PM part216.htm"">12/20/18, 2558 PM part217.htm"">12/20/18, 7516 PM part218.htm"">12/21/18, 4516 PM part219.htm"">12/21/18, 7510 PM part220.htm"">12/25/18, 10518 PM part221.htm"">1/1/19, 10540 AM part222.htm"">1/1/19, 3521 PM part223.htm"">1/3/19, 6501 PM part224.htm"">1/4/19, 11540 AM part225.htm"">1/4/19, 2501 PM part226.htm"">1/4/19, 3555 PM part227.htm"">1/6/19, 2519 PM part228.htm"">1/7/19, 9531 AM part229.htm"">1/7/19, 11527 AM part230.htm"">1/7/19, 9532 PM part231.htm"">1/8/19, 10534 PM part232.htm"">1/9/19, 1512 PM part233.htm"">1/10/19, 9551 AM part234.htm"">1/10/19, 5537 PM part235.htm"">1/11/19, 12526 PM part236.htm"">1/14/19, 12522 PM part237.htm"">1/13/19, 6555 PM part238.htm"">1/11/19, 1557 PM part239.htm"">1/17/19, 9539 AM part240.htm"">1/17/19, 3513 PM part241.htm"">1/18/19, 1505 PM part242.htm"">1/18/19, 2549 PM part243.htm"">1/22/19, 9557 AM part244.htm"">1/22/19, 3530 PM part245.htm"">1/24/19, 12532 PM part246.htm"">1/24/19, 2554 PM part247.htm"">1/25/19, 2554 PM part248.htm"">1/29/19, 9552 AM part249.htm"">1/30/19, 8528 AM part250.htm"">1/30/19, 11550 AM part251.htm"">2/1/19, 9506 AM part252.htm"">2/1/19, 11529 AM part253.htm"">2/1/19, 12557 PM part254.htm"">2/1/19, 4522 PM part255.htm"">2/2/19, 8519 AM part256.htm"">2/5/19, 1500 PM part257.htm"">2/5/19, 3537 PM part258.htm"">2/7/19, 2534 PM part259.htm"">2/8/19, 3526 PM part260.htm"">2/8/19, 5510 PM part261.htm"">2/11/19, 4538 PM part262.htm"">2/12/19, 10555 AM part263.htm"">2/13/19, 2514 PM part264.htm"">2/13/19, 4533 PM part265.htm"">2/13/19, 8537 PM part266.htm"">2/14/19, 8544 AM part267.htm"">2/14/19, 10516 AM part268.htm"">2/14/19, 11543 AM part269.htm"">2/16/19, 2501 PM part270.htm"">2/16/19, 3541 PM part271.htm"">2/19/19, 7501 PM part272.htm"">2/20/19, 10526 AM part273.htm"">2/20/19, 12501 PM part274.htm"">2/20/19, 4534 PM part275.htm"">2/24/19, 10550 AM part276.htm"">2/24/19, 12506 PM part277.htm"">2/24/19, 12506 PM part278.htm"">2/25/19, 1541 PM part279.htm"">2/25/19, 4554 PM part280.htm"">2/28/19, 2522 PM part281.htm"">3/6/19, 12522 PM part282.htm"">3/7/19, 12522 PM part283.htm"">3/7/19, 4517 PM part284.htm"">3/8/19, 2534 PM part285.htm"">3/12/19, 7514 PM part286.htm"">3/13/19, 11546 AM part287.htm"">3/13/19, 12552 PM part288.htm"">3/14/19, 2502 PM part289.htm"">3/15/19, 12545 PM part290.htm"">3/15/19, 4553 PM part291.htm"">3/18/19, 10522 AM part292.htm"">3/18/19, 11544 AM part293.htm"">3/18/19, 2536 PM part294.htm"">3/18/19, 4513 PM part295.htm"">3/19/19, 10506 AM part296.htm"">3/19/19, 1543 PM part297.htm"">3/20/19, 10530 AM part298.htm"">3/24/19, 11516 AM part299.htm"">3/24/19, 1533 PM part300.htm"">3/26/19, 8530 AM part301.htm"">3/28/19, 9507 PM part302.htm"">3/29/19, 8523 AM part303.htm"">4/2/19, 10504 AM part304.htm"">4/2/19, 11534 AM part305.htm"">4/2/19, 1508 PM "; 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