Shulou(Shulou.com)06/03 Report--

1. Regular expressions

() is to extract matching strings. There are several () in the expression, there are several corresponding matching strings.

(\s*) A string representing consecutive spaces.

(\d*) represents a continuous number, similar to [0-9]+

[] is the character range that defines the match. For example,[a-zA-Z0-9] indicates that the characters in the corresponding position should match English characters and numbers. [\s*] indicates a space or an *.

{} is generally used to indicate the length of the match, such as\s{3} for matching three spaces,\s[1,3] for matching one to three spaces.

(0-9)Matches '0-9' itself. [0-9]* Matching digits (note *, can be empty)[0-9]+ matching digits (note +, can not be empty){1-9} is written incorrectly.

[0-9]{0,9} represents a numeric string of length 0 to 9

Examples of []* and []+:

[]* can return control, that is, can not find the value, but [0-9]+ can not be empty, if empty return error

>>> c='GET /diviner? pin=1123066825_m&p='

>>> r=re.search('p=([0-9]+)',c)

>>> print r.group(1)

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'NoneType' object has no attribute 'group'

>>> print r

None

>>> r=re.search('p=([0-9]*)',c)

>>> print r.group(1)

---Return empty here

2.re mathc search Description

match () function only checks if RE matches at the beginning of string,

search() scans the entire string for a match;

>>> a='123aaabcabcabc'

>>> import re

>>> re.search('abc',a)

>>> re.mathc('abc',a)

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'module' object has no attribute 'mathc'

>>> re.match('abc',a)

>>> b=re.match('abc',a)

>>> print b

None

>>> b=re.match('1',a)

>>> pint b

File "", line 1

pint b

^

SyntaxError: invalid syntax

>>> print b

() in the role of group groups---mainly plays the role of grouping

>>> c='GET /diviner? pin=1123066825_m&p=61234'

>>> r=re.search('p=((\d*))',c)

>>> print c.group(0)

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'str' object has no attribute 'group'

>>> print r.group(0)

p=61234

>>> r=re.search('p=((\d*))',c)

>>> r=re.search('p=([0-9]*)',c)

>>> r=re.search('p=[0-9]*',c)

>>> print r.group

>>> print r.group(0)

p=61234

>>> print r.group (1)---No parenthesis No grouping

Traceback (most recent call last):

File "", line 1, in

IndexError: no such group

>>> r=re.search('p=([0-9]*)',c)

>>> print r.group(1)

61234

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