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

Substitution
Processing...

Code Generator

Language

Generated Code

import re regex = re.compile(r"^Hi.*Page (\d+).*\n(.*)", flags=re.MULTILINE) test_str = ("Notes and highlights for\n" "Outlive\n" "Attia MD, Peter\n" "Part I\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 10 · Location 150\n" "In 1900 , life expectancy hovered somewhere south of age fifty , and most people were likely to die from “ fast ” causes : accidents , injuries , and infectious diseases of various kinds . Since then , slow death has supplanted fast death . The majority of people reading this book can expect to die somewhere in their seventies or eighties , give or take , and almost all from “ slow ” causes .\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 10 · Location 154\n" "Four Horsemen : heart disease , cancer , neurodegenerative disease , or type 2 diabetes and related metabolic dysfunction .\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 10 · Location 155\n" "we must understand and confront these causes of slow death .\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 10 · Location 158\n" "Healthspan is typically defined as the period of life when we are free from disability or disease ,\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 14 · Location 215\n" "It is absurd and harmful to treat this disease like a cold or a broken bone , where you either have it or you don’t ; it’s not binary .\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 14 · Location 218\n" "Changing that mindset must be our first step in attacking slow death . We want to delay or prevent these conditions so that we can live longer without disease , rather than lingering with disease .\n" "Highlight (yellow) - Chapter 1: The Long Game: From Fast Death to Slow Death > Page 17 · Location 270\n" "Exercise is by far the most potent longevity “ drug . ” No other intervention does nearly as much to prolong our lifespan and preserve our cognitive and physical function .") subst = "> $2 [@attia:2023 p.$1]\\n" result = regex.sub(subst, test_str) 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