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
No Match

r"
"
g

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"(//[^\n]+)|(/\*.*?\*/)" test_str = ("#define MC2\n" "#define MC1\n\n" "# ifndef MCTEST\n" "#define MCTEST\n" " \n" "#ifdef MC1 \n\n" "#define data1 0x20\n" "/*cmment start*/#define /*this is comment*/ data2 2.5f\n" "#define date3 L\"this is a data\"\n" "#define data4 true\n\n\n" "#ifdef MC2\n\n" "#define data5 'a'\n" "#define data6 { {2.0, \"abc\"}, {1.5, \"def\"}, {5.6f, \"7.2\"}} // ¸¡µãÓë×Ö·û´®×é³ÉµÄ½á¹¹Ìå³õʼ»¯¾ÛºÏ£¬ ÔÙ½øÒ»²½¾ÛºÏ×é³ÉÁËÊý×é\n\n" "#else //else MC2\n\n" "# define data5 {5.0, 7.5, 3.8}\n" "#define data6 'c'\n\n" "#endif //end MC2\n\n" "#ifdef MC3\n" " //¼ÙifǶÌ×£¬ÓÃÓÚ²âÊÔ£¬ÔÚÓ¦¸Ã±»ºöÂÔµÄÇé¿öÏ£¬#endifµÄ¼æÈÝÇé¿ö\n" "#endif //end MC3\n\n" "#else//else MC1\n" "\"//ccc\"\n" "\"/*bbb*/\"\n" "\"/**/\"\n" "//\"//bbb\"\n" "/*\"jjjjj\"*/\n" "#define data1 1.0f /* this is float\n" "may be changed\n" "*/\n" "#define data2 2\n" "#define date3 false\n" "#define data4 \"this is a data\"\n\n\n" "#ifdef MC2\n\n" "#define data5 'B'\n" "#define data6 {1, 6, 3}\n" "#define data7 0xa\n\n" "#else//else MC2\n\n" "#define data5 'D'\n" "#define data6 {1, 6}\n\n" "#endif //end MC2\n\n" "#endif //MC1\n\n" "#ifdef MC2\n" "#undef MC2\n" "#endif\n\n" "/*ÔÚ¶àÐÐ×¢ÊͺóÃæ½ô¸úÒ»¸öµ¥ÐÐ×¢ÊÍ*///½ô¸úµÄµ¥ÐÐ×¢ÊÍ\n\n" "#endif // !MC_TEST") matches = re.finditer(regex, test_str) 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