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

const regex = /\s+([\d]+[*]*[\.]*[\d]*[\.]*[\d]*)/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('\\s+([\\d]+[*]*[\\.]*[\\d]*[\\.]*[\\d]*)', 'gm') const str = `PORO -- Generated : Petrel -- Property name in Petrel : PHIT_Object Cutoff60 28*0.00 0.03 0.03 9502*0.00 0.01 0.01 9502*0.00 0.01 0.01 9502*0.00 0.02 0.02 9502*0.00 0.02 0.01 9502*0.00 0.03 0.02 0.00 0.00 9500*0.00 0.02 0.03 9502*0.00 0.03 0.02 9502*0.00 0.03 0.03 9502*0.00 0.01 0.01 9502*0.00 0.01 0.01 0.02 9501*0.00 0.01 0.01 0.01 9501*0.00 0.02 0.03 0.02 9501*0.00 0.01 0.01 0.01 9501*0.00 0.02 0.02 0.02 9501*0.00 0.02 0.02 0.02 9501*0.00 0.01 0.02 0.02 0.00 9500*0.00 0.01 0.02 0.02 9501*0.00 0.01 0.01 0.01 9501*0.00 0.02 0.02 0.02 9501*0.00 0.03 0.02 0.02 5*0.00 0.03 0.03 0.00 0.00 9492*0.00 0.04 0.04 0.04 5*0.00 0.03 0.01 9494*0.00 0.01 0.02 0.02 5*0.00 0.02 0.02 9494*0.00 0.01 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.02 9493*0.00 0.01 0.01 0.01 5*0.00 0.01 0.01 0.01 9493*0.00 0.03 0.04 0.02 0.02 0.00 0.00 0.00 0.00 0.02 0.03 0.03 9493*0.00 0.01 0.01 0.01 0.01 0.00 0.00 5*0.01 9499*0.00 5*0.02 9493*0.00 0.03 0.03 0.03 0.04 0.00 0.00 0.03 0.02 0.02 0.02 0.02 9493*0.00 0.03 0.02 0.01 0.01 0.00 6*0.01 9493*0.00 0.01 0.01 0.01 0.02 0.00 0.01 0.01 0.01 0.01 0.02 0.02 0.00 0.00 0.00 9490*0.00 0.03 0.03 0.02 0.02 0.00 0.01 0.02 0.01 0.02 0.01 0.02 9494*0.00 0.03 0.01 0.01 0.00 0.01 0.01 0.01 0.01 0.02 0.02 0.00 9492*0.00 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.02 0.02 0.01 0.03 9493*0.00 0.02 0.02 0.02 8*0.01 9493*0.00 0.03 0.03 0.02 0.02 0.01 0.01 0.02 0.02 0.02 0.02 0.03 9493*0.00 5*0.02 0.01 0.01 0.01 0.01 0.02 0.03 9494*0.00 0.03 0.01 0.02 0.03 0.02 0.02 0.03 0.02 0.02 0.03 0.02 9496*0.00 0.01 0.01 0.01 0.01 0.00 0.00 0.02 0.03 9496*0.00 0.02 0.01 0.02 0.01 0.03 0.03 0.03 0.01 0.00 0.00 9495*0.00 0.01 0.00 0.01 0.01 0.01 0.02 0.01 0.01 9500*0.00 0.01 0.01 9495*0.00 0.02 0.03 0.01 0.01 0.02 0.01 0.02 0.02 0.03 0.03 0.03 421*0.00 0.03 53*0.00 0.06 2560*0.00 0.06 53*0.00 0.05 6402*0.00 0.02 0.02 0.03 0.02 0.03 0.02 0.02 0.03 0.03 0.03 0.03 0.00 420*0.00 0.06 53*0.00 0.07 2560*0.00 0.06 53*0.00 0.04 6402*0.00 0.03 0.04 0.03 5*0.02 0.03 0.03 0.03 421*0.00 0.07 0.00 0.00 0.00 50*0.00 0.07 2560*0.00 0.06 53*0.00 0.05 6402*0.00 0.02 0.02 0.03 0.02 0.02 0.01 0.02 0.02 0.03 0.03 0.03 421*0.00 0.05 0.00 0.00 51*0.00 0.06 2560*0.00 0.07 6456*0.00 0.01 0.04 0.03 0.01 0.02 0.00 0.00 0.02 0.02 0.02 0.01 421*0.00 0.06 0.00 0.00 0.00 0.00 49*0.00 0.07 2560*0.00 0.08 53*0.00 0.07 53*0.00 0.06 6348*0.00 0.03 0.03 0.03 0.00 0.00 0.00 0.00 0.02 0.02 0.02 0.01 0.00 0.00 419*0.00 0.06 53*0.00 0.07 2560*0.00 0.08 53*0.00 0.07 6402*0.00 0.04 0.04 0.04 5*0.00 0.03 0.03 0.03 421*0.00 0.05 0.00 0.00 0.00 50*0.00 0.06 2506*0.00 0.06 53*0.00 0.05 53*0.00 0.06 6402*0.00 0.01 8*0.00 0.03 476*0.00 0.06 2506*0.00 0.07 0.00 0.00 0.00 0.00 49*0.00 0.06 53*0.00 0.05 53*0.00 0.04 6508*0.00 0.01 108*0.00 0.02 162*0.00 0.05 53*0.00 0.06 2506*0.00 0.06 0.00 0.00 0.00 0.00 49*0.00 0.05 53*0.00 0.06 9395*0.00 0.08 6509*0.00 9*0.01 45*0.00 0.01 106*0.00 0.01 108*0.00 0.02 162*0.00 0.04 0.00 0.00 0.00 50*0.00 0.05 53*0.00 0.02 1712*0.00 0.02 7248*0.00 0.02 0.01 0.02 0.02 0.01 0.03 0.03 0.03 46*0.00 0.04 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.02 99*0.00 0.01 108*0.00 0.01 77*0.00 0.03 53*0.00 0.04 30*0.00 0.05 53*0.00 0.06 53*0.00 0.03 0.00 0.00 0.00 0.00 157*0.00 0.04 1550*0.00 0.03 102*0.00 0.03 636*0.00 0.07 53*0.00 0.08 6454*0.00 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.01 0.01 0.01 44*0.00 0.01 0.01 6*0.00 0.01 0.01 98*0.00 0.01 108*0.00 0.01 77*0.00 0.01 53*0.00 0.02 30*0.00 0.04 53*0.00 0.04 0.00 0.00 0.00 50*0.00 0.02 161*0.00 0.04 1550*0.00 0.05 102*0.00 0.05 636*0.00 0.07 53*0.00 0.07 53*0.00 0.06 6400*0.00 0.02 0.02 0.01 0.02 0.00 0.00 0.00 0.00 0.01 45*0.00 0.03 0.01 6*0.00 0.01 0.01 0.02 0.02 96*0.00 0.01 108*0.00 0.03 162*0.00 0.03 53*0.00 0.04 0.00 0.00 51*0.00 0.02 107*0.00 0.02 53*0.00 0.05 1550*0.00 0.02 102*0.00 0.03 636*0.00 0.10 2754*0.00 0.02 3753*0.00 0.01 0.01 0.01 0.02 0.02 0.01 0.00 0.00 0.01 45*0.00 0.02 0.01 6*0.00 0.01 99*0.00 0.01 108*0.00 0.02 162*0.00 0.05 53*0.00 0.07 0.00 0.00 0.00 0.00 49*0.00 0.04 107*0.00 0.04 53*0.00 0.07 1550*0.00 0.02 102*0.00 0.04 0.03 635*0.00 0.08 53*0.00 0.07 53*0.00 0.06 0.00 0.00 0.00 50*0.00 0.05 269*0.00 0.05 53*0.00 0.05 2268*0.00 0.03 53*0.00 0.03 3699*0.00 0.03 0.03 0.02 0.02 0.02 0.02 0.03 0.02 0.00 0.00 44*0.00 0.03 0.02 106*0.00 0.01 108*0.00 0.02 162*0.00 0.05 53*0.00 0.06 53*0.00 0.05 107*0.00 0.03 53*0.00 0.05 0.00 0.00 0.00 1650*0.00 0.04 636*0.00 0.07 53*0.00 0.08 53*0.00 0.05 53*0.00 0.04 323*0.00 0.04 6022*0.00 0.02 0.02 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.03 43*0.00 0.03 0.02 0.00 0.01 0.01 0.00 0.00 0.00 0.02 0.01 0.02 0.02 96*0.00 0.01 108*0.00 0.03 0.00 0.00 0.00 128*0.00 0.02 30*0.00 0.07 53*0.00 0.05 53*0.00 0.04 107*0.00 0.04 53*0.00 0.06 1653*0.00 0.03 690*0.00 0.06 0.00 0.00 0.00 0.00 49*0.00 0.04 53*0.00 0.05 269*0.00 0.04 53*0.00 0.04 2268*0.00 0.02 53*0.00 0.02 539*0.00 0.02 53*0.00 0.03 0.03 0.00 0.00 0.00 49*0.00 0.05 0.04 52*0.00 0.04 0.04 52*0.00 0.04 701*0.00 0.03 53*0.00 0.03 2187*0.00 0.01 0.01 0.02 0.02 0.02 0.02 0.00 0.01 0.00 0.01 0.03 43*0.00 0.03 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.03 96*0.00 0.01 108*0.00 0.04 131*0.00 0.02 0.00 0.00 28*0.00 0.04 53*0.00 0.05 53*0.00 0.03 107*0.00 0.02 53*0.00 0.05 5045*0.00 0.02 593*0.00 0.02 53*0.00 0.01 0.01 0.00 0.00 0.00 49*0.00 0.02 0.02 52*0.00 0.01 0.02 52*0.00 0.01 2943*0.00 0.04 0.04 0.00 0.03 0.02 0.02 0.00 0.02 0.00 0.02 0.00 0.00 0.00 0.00 40*0.00 0.05 0.03 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.02 0.03 97*0.00 0.02 108*0.00 0.03 162*0.00 0.05 53*0.00 0.07 0.00 0.00 51*0.00 0.05 107*0.00 0.04 53*0.00 0.06 5639*0.00 0.03 54*0.00 0.02 53*0.00 0.03 52*0.00 0.03 0.03 52*0.00 0.02 0.00 0.00 0.00 /`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions