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"""
"""
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"<img[^>]*alt=\"([^\"]+)\"[^>]*>" test_str = ("<span itemprop=\"description\"> <img src=\"//res.smzdm.com/images/emotions/30.png\" alt=\"[小怒]\" class=\"wp-smiley\"> <img src=\"//res.smzdm.com/images/emotions/30.png\" alt=\"[小怒]\" class=\"wp-smiley\"> <img src=\"//res.smzdm.com/images/emotions/30.png\" alt=\"[小怒]\" class=\"wp-smiley\"> 这文章百度哪里搬来的 </span>\n\n" "<span itemprop=\"description\"> <img src=\"//res.smzdm.com/images/emotions/36.png\" alt=\"[喜极而泣]\" class=\"wp-smiley\"> 年少无知看了那篇文章好奇买了4瓶 喝了一口差点吐出来 </span>\n\n" "<span itemprop=\"description\">国内咋就没厂商做点纯气泡水呢，成本应该不高吧，钱都让屈臣氏巴黎水赚去了 <img src=\"//res.smzdm.com/images/emotions/23.png\" alt=\"[皱眉]\" class=\"wp-smiley\"> </span>\n\n" "<span itemprop=\"description\">小时候就经常煲来喝，利尿排毒 <img src=\"//res.smzdm.com/images/emotions/45.png\" alt=\"[抽烟]\" class=\"wp-smiley\"> </span>\n\n" "<p class=\"p_content_166651051\"><span itemprop=\"description\">我喜欢香草味的，滑滑的感觉 </span></p>\n\n" "<p class=\"p_content_166650868\"><span itemprop=\"description\">我喝过好几箱，后来还回购了，再后来就喝不起了，太贵[皱眉] </span></p>") subst = "\\g<1>" # 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