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

Code Generator

Language

Generated Code

import re regex = re.compile(r""" @font-face\s* # Match @font-face and some spaces ( # Start group 1 \{ # Match { (?: # A non-capturing group [^{}]+ # Match anything except {} one or more times | # Or (?1) # Recurse/rerun the expression of group 1 )* # Repeat 0 or more times \} # Match } ) # End group 1 (*SKIP)(*FAIL) # Skip it | # Or url\s*\( # Match url, optionally some whitespaces and then ( \s* # Match optionally some whitespaces ("|'|) # It seems that the quotes are optional according to http://www.w3.org/TR/CSS2/syndata.html#uri (?!["']?(?:https?://|ftp://)) # Put your negative-rules here (do not match url's with http, https or ftp) (?:[^\\]|\\.)*? # Match anything except a backslash or backslash and a character zero or more times ungreedy \2 # Match what was matched in group 2 \s* # Match optionally some whitespaces \) # Match ) """, flags=re.VERBOSE | re.DOTALL) test_str = (".someclass0 {\n" " background: url('http://images/someimage.png') no-repeat;\n" "}\n\n" "@font-face {\n" " font-family: 'FontAwesome';\n" " src: url(\"fonts/fontawesome-webfont.eot?v=4.0.3\");\n" " src: url(\"fonts/fontawesome-webfont.eot?#iefix&v=4.0.3\") format(\"embedded-opentype\"), url(\"fonts/fontawesome-webfont.woff?v=4.0.3\") format(\"woff\"), url(\"fonts/fontawesome-webfont.ttf?v=4.0.3\") format(\"truetype\"), url(\"fonts/fontawesome-webfont.svg?v=4.0.3#fontawesomeregular\") format(\"svg\");\n" " font-weight: normal;\n" " font-style: normal;\n" "}\n\n" ".someclass1 {\n" " background: url('images/someimage.png') no-repeat;\n" "}\n\n" ".someclass2 {\n" " background: url(\"images/someimage.png\") no-repeat;\n" "}\n\n" ".someclass3 {\n" " background: url(images/someimage.png) no-repeat;\n" "}") 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