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This article will explain in detail how to correctly use regular expressions in python regular expressions, the content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Now that we've seen some simple regular expressions, how do we actually use them in Python? The re module provides an interface to the regular expression engine that allows you to compile REs into objects and use them for matching.

Compile regular expressions

Regular expressions are compiled into an instance of `RegexObject`, which provides methods for different operations, such as pattern matching search or string replacement.

#! python > import re > p = re.compile ('ab*')

> print pre

.compile ()

Optional flag parameters are also accepted and are often used to implement different special functions and syntax changes. We'll look at all the available settings later, but for now just one example:

#! python > p = re.compile ('ab*', re.IGNORECASE) RE

Is sent to re.compile () as a string. REs is treated as a string because regular expressions are not a core part of the Python language and no specific syntax is created for it. Applications don't need REs at all, so there's no need to include them to make the language specification bloated. The re module is only included by Python as a C extension module, just like the socket or zlib module.

Use REs as a string to keep the Python language concise, but one of the troubles is as described in the title of the next section.

[editor] the trouble of backslash

In the early days, regular expressions used the backslash character ("\") to indicate a special format or a special usage that allowed the use of a special character without calling it. This conflicts with the same characters that Python plays the same role in the string.

Let's illustrate that you want to write a RE to match the string "\ section", which may be looked up in a LATEX file. In order to judge in the program code, you must first write the string you want to match. Next you need to add a backslash to all backslashes and metacharacters to remove their special meaning.

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