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

/
/
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"\n(?=[^\"]+?\"\s*$)" test_str = ("ability,n. 能力，能耐；才能\n" "able,adj. 能； 有能力的；能干的\n" "about,\"prep. 关于；大约\n" "n. 大致；粗枝大叶；不拘小节的人\n" "adj. 在附近的；四处走动的；在起作用的\n" "adv. 大约；周围；到处\"\n" "above,\"prep. 超过；在……上面；在……之上\n" "n. 上文\n" "adj. 上文的\n" "adv. 在上面；在上文\"\n" "accident,n. 事故；意外； 意外事件；机遇\n" "accurate,adj. 精确的\n" "ache,\"n. 疼痛\n" "vi. 疼痛；渴望\"\n" "activity,n. 活动；行动；活跃\n" "actor,n. 男演员；行动者；作用物\n" "actress,n. 女演员\n" "actually,adv. 实际上；事实上") subst = " " # You can manually specify the number of replacements by changing the 4th argument result = re.sub(regex, subst, test_str, 0, re.MULTILINE) if result: print (result) # 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