Regular Expressions 101

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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]
  • Character class intersection
    [\w&&[^\d]]
  • 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"^(=?202\d)(\d{0,3}[A-Z]{1,4}|[A-Z]{1,4}\d{1,3})([\dA-Z]{0,4})A", flags=re.MULTILINE) test_str = ("Matches R1 R2 R3 R4 R5 R6\n" "2022A144A OK OK OK OK \\D\\d\\d\\d\n" "20228BC3A OK OK OK OK \\d\\D\\D\\d\n" "20228Z1DA OK OK OK OK \\d\\D\\d\\D\n" "2022K2 A \n" "20229999A NOK \\d\\d\\d\\d\n" "2022B123A OK OK OK OK \\D\\d\\d\\d\n" "20221B23A OK OK OK OK \\d\\D\\d\\d\n" "202212B3A NOK NOK NOK OK OK \\d\\d\\D\\d\n" "2022123BA NOK OK \\d\\d\\d\\D\n" "2022ABCDA \n" "2022K2 A \n\n" "Matches 100% as desired\n" "R 12 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w|\\d\\d\\w\\D|\\D\\D\\D\\D)A\n" "R 13 ^(=?202\\d)(\\d{0,3}[A-Z]{1,4}|[A-Z]{1,4}\\d{1,3})([\\dA-Z]{0,4})A\n\n\n" "Should match\n" "R1: 2022\\d\\D\\w\\wA\n" "R2: 2022\\D\\d\\w\\wA\n" "R3: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w)A\n" "R4: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w)A\n" "R5: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w|\\d\\d\\w\\D)A\n\n" "R 10 ^(=?202\\d)(\\d*[A-Z]|[A-Z]*)([\\dA-Z]{1,3})A\n" "R 11 ^(=?202\\d)(\\d{1,3}[A-Z]*)([\\dA-Z]{1,3})A\n" "R 12 ^(=?202\\d)(\\d{1,3}[A-Z]{1,3}|[A-Z]{1,3}\\d{1,3})([\\dA-Z]{0,3})A\n\n\n\n" "^ Start of string\n" "(?=[a-z\\d]{8,}$) Positive lookahead, assert 8 or more chars a-z or digits till end of string\n" "(?=\\d*[a-z]) Positive lookahead to assert at least a char a-z\n" "[a-z]* Match optional chars a-z\n" "\\d Match at least a single digit\n" "[a-z\\d]* Match optional chars a-z or digits\n" "$ End of string\n\n" "Should not match\n" "R6: 2022([A-Z0-9]{1,4})A\n" "R7: 2022(\\d|\\w){1,3}\\wA <-- also matches 20229999A which it should not\n" "R8: 2022\\w\\w\\s\\sA\n" "R9 2022\\d\\d\\d\\dA") 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