python There are many ways to intercept and replace strings

Time :2016-03-12 20:08:14 source : The Internet
Reading guide :python There are many ways to intercept and replace strings , Colon separated string interception method ,python String substitution method , In the way of the string itself , Or replace the string with regular .
 
from :http://www.xfcodes.com/python/zifuchuan/9398.htm
 
python There are many ways to intercept and replace strings

One , String truncation
Python Is an ordered set of strings , You can use the index to extract the characters you want to get , hold python As a list of strings, it's easier to understand .

python The list of strings for has 2 The order of values is :
The first is the left to right index 0 At the beginning , The maximum range is less string length 1:

Copy code example :
s = 'ilovepython'
s[0] The result is i
 

The second is the right to left index -1 At the beginning , The maximum range is at the beginning of the string :

Copy code example :
s = 'ilovepython'
s[-1] The result is n
 

This is to get a character , If you want to get a break , You can use python String interception function , such as :

Copy code example :
s = 'ilovepython'
s[1:5] The result is love
 

When using colon delimited strings ,python Return a new object , The result contains consecutive content identified by this pair of offsets , The start on the left contains the lower boundary , For example, the results above include s[1] Value l, The maximum range taken does not include the upper boundary , Namely s[5] Value p.
 
Give more examples :
s[:3]
The result is 'ilo', Omit : On the left , Silently, the index value from the left is 0, In fact, this expression is similar to s[0:3] It means the same .

s[:-1]
The result is :'ilovepytho' That is, the index value starting on the left is 0, The maximum range is to the last character in the string, but does not include the last character .
 
s[:]
The result is :'ilovepython' Got the offset from 0 Elements between the end , This is a python String copy .

Two ,python String substitution

python String substitution method .

Two ways to do python String substitution :

1、 In the way of the string itself replace Replace string .

2、 Replace string with regular .

Example :

Copy code example :
a = 'hello word'
 

hold a In a string word Replace with python.

1、 Using the string itself replace Method

Copy code example :
a.replace('word','python')
 

Output :
hello python

2、 Replace strings with regular expressions

Copy code example :
import re
strinfo = re.compile('word')
b = strinfo.sub('python',a)
print b
 

Output :
hello python

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