Python standard library 01 regular expressions

Source: Internet
Author: User

In the process of learning web crawler, it is necessary to crawl the number of comments on the Web page, involving regular expressions, and then look at the way. Regular expressions are a common tool in word processing.

1 common strings for regular expressions

. Any single character

The "" Character set gives a range of values for a single character

"^" Non-character set

* Previous character repeats 0 or more times

+ Previous character repeats 1 or more times

? Repeat 0 or 1 times for the previous character

| Or

{m} The previous character expands m times

{M,n} The previous character expands M to n times

^ Match string start

$ Match String End

\d "0-9"

\w Word characters

2 Main function functions

 Import re     # importing re package # searches the entire string until a matching string is found #  Matches the regular expression from the beginning of the string, returns the result m=re.sub (pattern,replacement,string)# finds and replaces M=re.findall () from the string  # search string, put all matching substrings in a table return # Returns the iteration type of a matching result, each iteration element is a match object m= Re.split ()     # splits a string according to the result of a regular expression match, returning the list type (number) View the results of the search, group (0) is the search result for the entire expression, group (1) is the first group, and so on.

Python standard library 01 regular expressions

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.