Regular expressions are a small, highly specialized programming language that is not unique to Python. It is a basic and important part of many programming languages. In python, it is mainly implemented through the re module.

Regular expression patterns are compiled into a series of bytecodes and then executed by a matching engine written in C. So what are the common usage scenarios of regular expressions?

For example, specify rules for the corresponding set of strings you want to match;

The string set can include e-mail addresses, Internet addresses, phone numbers, or some string sets customized according to needs;

Of course, you can also judge whether a string set conforms to the matching rules we defined;

Find the part of the string that matches the rule;

A series of text processing such as modification and cutting;