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"
"
gm

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "((http|https)+\\:\\/\\/)?([\\w\\d-]+\\.)*[\\w-]+[\\.\\:]\\w+([\\/\\?\\=\\&\\#\\.]?[\\w-]+)*\\/?"; final String string = "https://www.facebook.com\n" + "https://app-1.number123.com\n" + "http://facebook.com\n" + "ftp://facebook.com/faq\n" + "http://localhost:3000\n" + "localhost:3000/\n" + "unitedkingdomurl.co.uk\n" + "this.is.a.url.com/its/still=going?wow\n" + "shop.facebook.org\n" + "app.number123.com\n" + "app1.number123.com\n" + "app-1.numbEr123.com\n" + "app.dashes-dash.com\n" + "www.facebook.com\n" + "facebook.com\n" + "facebook.in\n" + "fb.com/hello_123\n" + "fb.com/hel-lo\n" + "fb.com/hello/goodbye\n" + "fb.com/hello/goodbye?okay\n" + "fb.com/hello/goodbye?okay=alright\n" + "Hello www.google.com World http://yahoo.com\n" + "https://www.google.com.tr/admin/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "https://google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "http://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "ftp://google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "www.google.com.tr/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "www.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "drive.google.com/test/subPage?qs1=sss1&qs2=sss2&qs3=sss3#Services\n" + "https://www.example.pl\n" + "http://www.example.com\n" + "www.example.pl\n" + "example.com\n" + "http://blog.example.com\n" + "http://www.example.com/product\n" + "http://www.example.com/products?id=1&page=2\n" + "http://www.example.com#up\n" + "http://255.255.255.255\n" + "http://255.255.255.255:8080/faq\n" + "255.255.255.255/faq\n" + "shop.facebook.org/derf.html\n\n" + "https://youtu.be/c30TltNg-Wk : this is valid\n" + "https://www.youtu.be/c30TltNg-Wk : this is invalid\n" + "www.youtu.be/c30TltNg-Wk : this is invalid\n" + "what should be there finally there in content info file?\n" + "youtu.be/c30TltNg-Wk or https://youtu.be/c30TltNg-Wk"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html