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

/
/
gmxXi

Test String

Code Generator

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r""" # ./configure parser ^(?: (?:configuring[[:space:]]for[[:space:]](.+)) | (?: checking[[:space:]] (?: (?:build|host) [[:space:]]system[[:space:]]type | how[[:space:]]to[[:space:]](.+?) | for[[:space:]](.+?) | whether[[:space:]](?:to[[:space:]])?(.+?) )[\.]{3} ) (?: [[:space:]]+ (?: $ | (?: (yes) | (no) | (?<!^)(.*)(?=$|\n) ) ) )?.* )$ # ^(?:(?:configuring[[:space:]]for[[:space:]](.+))|(?:checking[[:space:]](?:(?:build|host)[[:space:]]system[[:space:]]type|how[[:space:]]to[[:space:]](.+?)|for[[:space:]](.+?)|whether[[:space:]](?:to[[:space:]])?(.+?))[\.]{3})(?:[[:space:]]+(?:$|(?:(yes)|(no)|(?<!^)(.*)(?=$|\n))))?.*)$ """ test_str = ("configuring for zsh 5.7.1-test-2\n" "checking build system type... x86_64-apple-darwin17.7.0\n" "checking host system type... x86_64-apple-darwin17.7.0\n" "checking for gcc... gcc\n" "checking whether the C compiler works... yes\n" "checking for C compiler default output file name... a.out\n" "checking for suffix of executables... \n" "checking whether we are cross compiling... no\n" "checking for suffix of object files... o\n" "checking whether we are using the GNU C compiler... yes\n" "checking whether gcc accepts -g... yes\n" "checking for gcc option to accept ISO C89... none needed\n" "checking for special C compiler options needed for large files... no\n" "checking for _FILE_OFFSET_BITS value needed for large files... no\n" "checking how to run the C preprocessor... gcc -E\n" "checking for an ANSI C-conforming const... yes\n" "checking for gcc option to accept ANSI C... \n" "checking whether to use prototypes... yes\n" "checking for grep that handles long lines and -e... /usr/local/bin/ggrep\n" "checking for egrep... /usr/local/bin/ggrep -E\n" "checking for ANSI C header files... yes\n" "checking for sys/types.h... yes\n" "checking for sys/stat.h... yes\n" "checking for stdlib.h... yes\n" "checking for string.h... yes\n" "checking for memory.h... yes\n" "checking for strings.h... yes\n" "checking for inttypes.h... yes\n" "checking for stdint.h... yes\n" "checking for unistd.h... yes\n" "checking for size_t... yes\n" "checking for working alloca.h... yes") matches = re.finditer(regex, test_str, re.MULTILINE | re.VERBOSE | re.IGNORECASE) 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