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]
  • 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

Generated Code

import re regex = re.compile((r"(?xXmi)\n" r"(?:\n" r" (?# use non-capture for details in debugging)\n" r" (?:\n" r" (?<match>\n" r" (?# If quoted value)\n" r" (?<quot_char>(?<!\\)[\"'])\n" r" (?# Quoted content)\n" r" (?:\n" r" (?:\n" r" (?# Match as many characters that aren't quotation char)\n" r" (?# or escape char as possible. )\n" r" (?:(?:(?!\k<quot_char>|\\)).+)\n" r" (?:\n" r" (?# Match any/all escape chars that do not have the)\n" r" (?# quotation char following it. )\n" r" (?:(?:\\)*(?!\k<quot_char>))?\n" r" (?# If there is an escape char followed by the quotation)\n" r" (?# quotation char match them. )\n" r" (?:[\\]\k<quot_char>)?\n" r" )*?\n" r" )\n" r" )\n" r" (?<close_quot>\k<quot_char>)\n" r" |\n" r" (?# if simple token)\n" r" (?<basic>[^ \n]+)+\n" r" )\n" r" )\n" r" (?<trail_ws>[ ]+)?\n" r")"), flags=re.MULTILINE) test_str = ("-t1a1\n" "-t2a1 -t2a2\n" " -t3a1 -t3a2 \n" "-t4a1 Test1value -t4a2 test4a2value -t4a3 t4a3value\n" "-t5a1EscQuot \\'t5a1valueESQ\\' -t5a2EscQuot \\\"t5a2valueEDQ\\\"\n" "-t6a1 \"t6a1value1DQWord1 t6a1value1DQWord1\" -t6a2SQuot 't6a2value1SQWord1 t6a2value1SQWord2 t6a2value1SQWord3 '\n" "-t7a1SQuotEmpty '' -t7a2DQuotEmpty \"\"\n") subst = "\\n${match}" 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