Regular Expressions 101

Save & Manage Regex

  • Current Version: 1
  • Save & Share
  • Community Library

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
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

Code Generator

Language

Generated Code

import re regex = re.compile(r"((([a-z]\[[^\]]+\])(.{1}))?(\s*\=\>\s*)((([a-z]\[[^\]]+\])|([a-z].))(.{1})([A-Z]?)))?(\s*\/\/.*)?") test_str = ("// Алгоритм умножения. Формат ленты: [*]1111#111=*\n" "// Множество: Q; Начальное значение: q[0]; Конечное значение: q*;\n" "// Символ пустой ячейки: _; Символ перехода влево: L; Символ перехода вправо: R\n" "q[0]1 => q[0]1R //2312312323\n" "q[0]# => q[1]#R\n" "q[0]* => q[0]*R\n" "q[1]1 => q[2]aR\n" "q[2]1 => q[2]1L\n" "q[2]# => q[3]#L\n" "q[2]= => q[2]=L\n" "q[2]a => q[2]aL\n" "q[3]1 => q[4]aR\n" "q[3]a => q[3]aL\n" "q[3]* => q[6]*R\n" "q[4]1 => q[4]1R\n" "q[4]# => q[4]#R\n" "q[4]= => q[4]=R\n" "q[4]a => q[4]aR\n" "q[4]* => q[5]1R\n" "q[5]_ => q[2]*L\n" "q[6]# => q[7]#R\n" "q[6]a => q[6]1R\n" "q[7]1 => q[2]aR\n" "q[7]= => q[8]=L\n" "q[7]a => q[7]aR\n" "q[8]# => q*#\n" "q[8]a => q[8]1L") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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