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

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?P<cdn_node_ip>\S+) - (?P<client_ip>\S+) - - \[(?P<date>\S+)\] "(?P<verb>\w+) (?P<url>\/(?P<delivery_type_code>\S+?)\/(?P<delivery_type>\S+?)\/(?P<bucket_id>\S+?)\/(?P<file_path>.*)) (?P<version>\S+) (?P<referrer_url>\S+)" (?P<status_code>\d+) (?P<content_length>\d+) (?P<bytes_transferred>\d+) (?P<duration>\d+) (?P<cached>-|\d+) "(?P<user_agent>.*?)" "(?P<ep_region_id>\d+) (?P<user_region_id>\d+) (?P<ep_pid>\d+) (?P<user_pid>\d+) (?P<hash_content>\S+)" "("|(?P<download_id>\d+) (?P<origin>\S+) (?P<retries>\d+) (?P<code>\d+) (?P<time>\d+) (?P<p2p>\d+)") (?P<host>\S+) (?P<request_id>\d+) (?P<http_request>\d+) (?P<cache_tier_name>\S+) (?P<layer>\d)`) var str = `10.95.151.28 - 10.95.151.253 - - [22/Jan/2019:10:41:45.956] "GET /P/0/_53/video_68473.fakevideo HTTP/1.1 -" 404 42 42 4019 - "curl/7.29.0" "1 2 1 2 03" "" b53.1.qacdndev.cdn.hi.inet 3 0 hdd 0` 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/