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

/
/
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 = "^\\s*((?:const\\s+|virtual\\s+|friend\\s+|volatile\\s+){0,4}\\s*?(?:\\w+\\s*::)?\\s*[\\w]+)\\s+(\\w+)\\s*\\([\\s\\S]*?\\)\\s*(const)?\\s*\\{"; final String string = "#include \"Port.h\"\n\n" + "namespace Port {\n\n" + " uint8_t lirePin(volatile uint8_t * pin)\n" + " {\n" + " return * pin;\n" + " }\n" + " /*********************************************************************\n" + " * retourne vrai si les pin du port pin sont ouvert\n" + " * pin = PINA a PIND\n" + " *********************************************************************/\n" + " bool lirePin(uint8_t pins, volatile uint8_t * pin)\n" + " {\n" + " return (*pin & pins);\n" + " }\n" + " /*********************************************************************\n" + " * Met la pin du port port a 5V\n" + " * port = PORTA a PORTD\n" + " *********************************************************************/\n" + " void ouvrirPin(uint8_t pins, volatile uint8_t * port)\n" + " {\n" + " *port |= pins;\n" + " }\n" + " /*********************************************************************\n" + " * Met la pin du port port a 0V\n" + " * port = PORTA a PORTD\n" + " *********************************************************************/\n" + " void fermerPin(uint8_t pins, volatile uint8_t * port)\n" + " {\n" + " *port &= ~pins;\n" + " }\n" + " /*********************************************************************\n" + " * Met la pin du port ddr en Entree\n" + " * ddr = DDRA a DDRD\n" + " *********************************************************************/\n" + " void pinEntree(uint8_t pins, volatile uint8_t * ddr)\n" + " {\n" + " *ddr &= ~pins;\n" + " }\n" + " /*********************************************************************\n" + " * Met la pin du port ddr en Sortie\n" + " * ddr = DDRA a DDRD\n" + " *********************************************************************/\n" + " const volatile friend std::void pinSortie(uint8_t pins, \n" + "volatile uint8_t * ddr)\n" + " {\n" + " *ddr |= pins;\n" + " }\n" + " /*********************************************************************\n" + " * Met le port ddr en Entree\n" + " * ddr = DDRA a DDRD\n" + " *********************************************************************/\n" + " void portEntree(volatile uint8_t * ddr) const\n" + " {\n" + " *ddr = ENTREE;\n" + " }\n" + " /*********************************************************************\n" + " * Met le port ddr en Entree\n" + " * ddr = DDRA a DDRD\n" + " *********************************************************************/\n" + " void portSortie(volatile uint8_t * ddr)\n" + " {\n" + " *ddr = SORTIE;\n" + " }\n" + " \n" + "}\n"; 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