Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
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
Processing...

Test String

Substitution
Processing...

Code Generator

Language

Generated Code

import re regex = re.compile((r"interface GigabitEthernet1\/(1[2-9]|[1-2][0-1]).*\n(.*\n)*.* description \*\* Unused Port \*\*.*\n(.*\n)*.* switchport access vlan 1002.*\n(.*\n)*.* switchport mode access.*\n(.*\n)*.* switchport port-security.*\n(.*\n)*.* switchport port-security mac-address sticky.*\n(.*\n)*.* shutdown.*\n(.*\n)*.* no cdp enable.*\n(.*\n)*.* spanning-tree portfast\n")) test_str = ("interface GigabitEthernet1/12\n" " description ** Unused Port **\n" " switchport access vlan 1002\n" " switchport mode access\n" " switchport port-security\n" " switchport port-security mac-address sticky\n" " shutdown\n" " no cdp enable\n" " spanning-tree portfast\n" "!\n" "interface GigabitEthernet1/13\n" " description ** Unused Port **\n" " switchport access vlan 1002\n" " switchport mode access\n" " switchport port-security\n" " switchport port-security mac-address sticky\n" " shutdown\n" " no cdp enable\n" " spanning-tree portfast\n" "!\n") subst = "" result = regex.sub(subst, test_str, count=1) if result: print(result)

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 Python, please visit: https://docs.python.org/3/library/re.html