3.2.1 Regular Expression syntax (1), 3.2.1 Regular Expression

3.2.1 Regular Expression syntax (1), 3.2.1 Regular Expression

(?...)

This syntax rule is an extension of the previous syntax. It can be replaced with a specific character at the question mark position.

Example:

Print ('(?...) ')

M = re. findall (R' (a...) ', r'abcdefaghijk ')

If m:

Print (m)

The output result is as follows:

(?...)

['Abcd', 'aghi']

(? #...)

Comment out the brackets, which does not work. Skip these rules during regular expression analysis.

Example:

Print ('(? # )')

M = re. findall (U '(? # A) I ', u'ailmsux aaaadefagaiLmsuxhijk ')

If m:

Print (m)

The output result is as follows:

(? #)

['I', 'I', 'I']

 

(? = ...)

Forward recognition mode. When the forward character matches the character in the equal sign, it is considered to be matched, but these characters are not skipped. For example, Isaac (? = Asimov), the Isaac is recognized only when the Asimov character is reached after the Isaac character, but the Asimov won't jump over.

Example:

Import re

 

 

Print ('isaac (? = Asimov )')

M = re. findall (u'isaac (? = Asimov) ', u'abcdisaacasimovttttt ')

If m:

Print (m)

The output result is as follows:

Isaac (? = Asimov)

['Isaac ']

Cai junsheng QQ: 9073204 Shenzhen

Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.