上QQ阅读APP看书，第一时间看更新

Getting ready

The python module to deal with regexes is called re. The main function we'll cover is re.search(), which returns a match object with information about what matched the pattern.

As regex patterns are also defined as strings, we'll differentiate them by prefixing them with an r, such as r'pattern'. This is the Python way of labeling a text as raw string literals, meaning that the string within is taken literally, without any escaping. This means that a \ is used as a backslash instead of a sequence. For example, without the r prefix, \n means newline character.

Some characters are special, and refer to concepts such as the end of the string, any digit, any character, any whitespace character, and so on.

The simplest form is just a literal string. For example, the regex pattern r'LOG' matches the string 'LOGS', but not the string 'NOT A MATCH'. If there's not a match, search returns None:

>>> import re
>>> re.search(r'LOG', 'LOGS')
<_sre.SRE_Match object; span=(0, 3), match='LOG'>
>>> re.search(r'LOG', 'NOT A MATCH')
>>>