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 (1)

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

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} \S+ \(\S+\) - flush done sketch={flushed=(\d+) total=(\d+) pruned=(\d+)} num_org_metric=\d+ since_ms=(\d+)ms dt=[-+]?([0-9]*(\.[0-9]*)?[a-z]+)+`) var str = `2018-03-05 22:52:52 INFO (app.go:391) - flush done sketch={flushed=264557 total=57979680 pruned=295} num_org_metric=448 since_ms=10964ms dt=2.2392s 2018-03-05 22:53:01 INFO (app.go:391) - flush done sketch={flushed=171045 total=57954960 pruned=253} num_org_metric=448 since_ms=9377ms dt=1.616403s 2018-03-05 22:53:10 INFO (app.go:391) - flush done sketch={flushed=190064 total=57933000 pruned=297} num_org_metric=448 since_ms=9366ms dt=982.968ms 2018-03-05 22:53:20 INFO (app.go:391) - flush done sketch={flushed=153243 total=57932520 pruned=89} num_org_metric=448 since_ms=9908ms dt=891.573ms` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", 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 Golang, please visit: https://golang.org/pkg/regexp/