python 语法糖

什么是语法糖？

语法糖是编程的一种更加简洁的特殊写法。

1.交换两个变量的值

a,b = b,a

2.判断变量是否在范围内

a = 97
if 90 < a < 100:
	print("a在90-100范围内")

3.快速构造字符串

# print('------------------------------')
print('-'*60)
print("*"*20)

4.列表拼接

a = [1,2,3,4]
b = [5,6,7,8]
a + b 

5.列表切片

a=[1,2,3,4,5,6,7,8,9]
a[3,-2]
a[:3]
a[-3:]

6.打包与解包

a=(1,2,3)
x,y,z = a
b = (x,y,z)

7.with语句

with open("file1.txt",'r') as f:
	data = f.read()

8.列表推导式

a = [1,2,3,4]
b = [i + 233 for i in a]