Detailed explanation of how to use strip() and split() in python

This article mainly introduces the detailed explanation and examples of the python strip() function and split() function. Friends in need can refer to

python strip() function and split( ) Detailed explanation and examples of functions

I have never been able to distinguish the functions of strip and split. In fact, strip means delete; and split means splitting. Therefore, it also means that the two functions are completely different. Strip can delete certain characters of string, while split splits the string according to the specified characters. Let’s talk about these two functions in detail below.

1 Python strip() function introduction

Function prototype

Declaration: s is a string, rm is the character sequence to be deleted

s.strip(rm) Delete the characters at the beginning and end of the s string, located in the rm deletion sequence

s.lstrip(rm) Delete the s character The character at the beginning of the string, located in the rm deletion sequence

s.rstrip(rm) Delete the character at the end of the s string, located in the rm deletion sequence

Note:

(1) When rm is empty, whitespace characters (including '\n', '\r', '\t', ' ') are deleted by default.

(2)Here The rm deletion sequence is to delete the characters on the edge (beginning or end) as long as they are within the deletion sequence.

For example,

>>> a = '  123' 
>>> a 
'  123' 
>>> a.strip() 
'123'

(2) The rm deletion sequence here is to delete the characters on the edge (beginning or end) as long as they are within the deletion sequence.

For example,

>>> a = '123abc' 
>>> a.strip('21') 
'3abc' 
>>> a.strip('12') 
'3abc'

The result is the same.

2 python split() function introduction

Explanation:

There is no character type in Python In other words, there is only the string . The character mentioned here is a string containing only one character! ! !

The reason why it is written like this is just for the convenience of understanding, nothing more.

(1) Split by a certain character, such as '.'

>>> str = ('www.google.com') 
>>> print str 
www.google.com 
>>> str_split = str.split('.') 
>>> print str_split 
['www', 'google', 'com']

(2) Split by a certain character, and split n times. For example, press '.' to split once

>>> str_split = str.split('.',1) 
>>> print str_split 
['www', 'google.com']

(3) You can also add regular expression after the split() function, for example:

>>> str_split = str.split('.')[0] 
>>> print str_split 
www

after split is a List, [0] means taking the first element;

>>> str_split = str.split('.')[::-1] 
>>> print str_split 
['com', 'google', 'www'] 
>>> str_split = str.split('.')[::] 
>>> print str_split 
['www', 'google', 'com']

Arrange in reverse order, [::] Arrange in positive order

>>> str = str + '.com.cn' 
>>> str 
'www.google.com.com.cn' 
>>> str_split = str.split('.')[::-1] 
>>> print str_split 
['cn', 'com', 'com', 'google', 'www'] 
>>> str_split = str.split('.')[:-1] 
>>> print str_split 
['www', 'google', 'com', 'com']

From the first element to the end, the last one The element is deleted.

One of the typical applications of the split() function, ip number exchange:

# ip ==> number

>>> ip2num = lambda x:sum([256**j*int(i) for j,i in enumerate(x.split('.')[::-1])]) 
>>> ip2num('192.168.0.1') 
3232235521

# number ==> ip # number range [0, 255^4]

>>> num2ip = lambda x: '.'.join([str(x/(256**i)%256) for i in range(3,-1,-1)]) 
>>> num2ip(3232235521) 
'192.168.0.1'

Finally, how does Python convert an integer to an IP address?

>>> import socket 
>>> import struct 
>>> int_ip = 123456789 
>>> socket.inet_ntoa(struct.pack(‘I',socket.htonl(int_ip)))#整数转换为ip地址 
‘7.91.205.21' 
>>> str(socket.ntohl(struct.unpack(“I”,socket.inet_aton(“255.255.255.255″))[0]))#ip地址转换为整数 
‘4294967295'

【Related recommendations】

1. Python free video tutorial

2. Detailed explanation of the usage scenarios of strip function in python

3. The little-known traps of strip() in python

4. The wonderful uses of strip() function in Python that you don’t know

5. Basic introduction to python teaches you how to use the strip() function to remove spaces\n\r\t

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