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

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"(\d+)\s+(\w{2})\s*(\w{2,5})\s+(\w{5})(?:\s+|\s+(.)\s+)(\w{3})(\w{3})(?:\s+|(?:\s|\*)(\w{3})\s+)(\w{4,5})\s+(\w{4,5})(?:\s+(\w{5}))?.*(?:\n|$)??((?:.|\n)*?)(\n\s*\n)?(?=\d+\s+\w{2}\s*\w{2,5}\s+\w{5}(?:\s+|\s+.\s+)\w{3}\w{3}(?:\s+|(?:\s|\*)\w{3}\s+)\w{4,5}\s+\w{4,5}(?:\s+\w{5})?|$)" test_str = (" 1 UA 990J 28OCT SFOCDG 340P 1015A 29OCT greg\n" "2 AF1830J 31OCT CDGMXP 900A 1025A 31OCT\n" "OPERATED BY AIR CANADA\n" "YYZ CHECK-IN WITH AIR CANADA\n" "3 LH 259J 03NOV T MXPFRA 740A 900A 03NOV \n" "OPERATED BY LUFTHANSA\n" "MAD CHECK-IN WITH LUFTHANSA\n\n" "4 DL2252Z 01OCT T SATDTW*SS1 1246P 454P\n" "5 DL 98Z 01OCT T DTWCDG*SS1 608P 805A 02OCT W /DCDL /E\n" "6 DL8322Z 02OCT W CDGBOD*SS1 935A 1050A /DCDL /E\n" "OPERATED BY AIR FRANCE\n" "grggf rge\n" " \n" "7 DL9365Z 09OCT W BODAMS*SS1 1150A 140P /DCDL /E\n\n" "OPERATED BY KLM ROYAL DUTCH AIRLINES\n" "8 DL8178Z 09OCT W AMSSLC*SS1 500P 655P /DCDL /E\n" "OPERATED BY KLM ROYAL DUTCH AIRLINES\n\n\n" "fre\n\n" "f\n" "10 LH 454J 03NOV FRASFO 1005A 205P 03NOV\n\n" "11 LH 454J 03NOV SFOKIV 205P 235P 03NOV") matches = re.finditer(regex, test_str) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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