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

/
/
gm

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){3}(-| |)\1{2}\2\1{4})(?!666|000|9\d{2})(\b\d{3}(-| |)(?!00)\d{2}\4(?!0{4})\d{4}\b)" test_str = ("################\n" "## Must match:\n" "################\n\n" "123-45-4891\n" "098-18-6564\n" "123-45-4848\n" "702-02-0202\n" "001-14-0004\n" "009958881\n" "078-05-1120\n" "009 95 8881\n" "123-45-4891 is my ssn\n" "my ssn is 123-45-4891\n" "my ssn is 123-45-4891 ok?\n" "my ssn is 123-45-4891.\n" "123454891 is my ssn\n" "my ssn is 123454891\n" "my ssn is 123454891 ok?\n" "my ssn is 123454891.\n" "123 45 4891 is my ssn\n" "my ssn is 123 45 4891\n" "my ssn is 123 45 4891 ok?\n" "my ssn is 123 45 4891.\n" "my ssn is:123-45-4891.\n" "my ssn is:123 45 4891.\n" "my ssn is:123454891.\n\n" "################\n" "## Must not match:\n" "################\n\n" "# Same number sequences:\n" "222-22-2222\n" "444 44 4444\n" "555555555\n\n" "# Telephone\n" "1-234-567-8901\n" "1-234-567-8901\n" "1-234-567-8901 \n" "1 (234) 567-8901\n" "12345678901\n\n" "# Credit card \n" "5500 0000 0000 0004\n" "3400 0000 0000 009\n" "3000 0000 0000 04\n" "5500-1244-2232-0004\n" "3400-1244-0000-009\n" "3000-1244-1234-04\n\n" "# mixed (space), dash and (no space)\n" "009 95-8881\n" "009-95 8881\n" "009 958881\n" "00995 8881\n\n" "# Zero sequence\n" "231-84-0000\n" "231-00-7289\n" "000-87-7289\n" "231 84 0000\n" "231 00 7289\n" "000 87 7289\n" "231840000\n" "231007289\n" "000877289\n\n" "# Starting with 9\n" "908-78-0485\n" "908 78 0485\n" "908780485\n\n" "# Random Numbers\n" "1234567890112371298739872891738912738937289d712897381297381927d3128937893d7218947d1892742189duc89789v127c897412987893c12893c79\n" "122-426-389\n" "187-5-43212\n" "187-0-43212\n" "2423-45-6789\n" "myssnnumberis123-45-4891ok?") matches = re.finditer(regex, test_str, re.MULTILINE) 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