Summary of key points to note in Python

This article introduces a summary of key points to note in python

1. Arithmetic operations are performed in python2.7 / The operation is not precise enough and you need to reference the _future_ class library

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from _future_ import division
 val = 9/2
  
 print(val)

2. Range and xrange

【python2.7】 The performance of xrange looping is better than range, especially when the return is very large. Try to use xrange, unless you want to return a list.

In python3.5, only range has the same function as xrange!

#!/usr/bin/env python
# -*- conding:utf-8 -*-
s1 = range(1,10)
s2 = xrange(1,5)
print(s1)
print(s2)
for s in s2:
    print s

3. The use of judging in or not in

#!/usr/bin/env python
# -*- conding:utf-8 -*-
li = "Alex SB"
ret = "Al" in li
print(ret) # => True
li = ["alex","eric","rain"] 
ret = "al" in li
print(ret) # => False

4. Classes and objects

【Python】str类方法说明

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