Python入门7 —— 赋值运算符补充

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增量赋值

x = 10
x += 1 #就是：x = x+1

交叉赋值

a = 10
b = 20
print(a,b)

temp=b # temp=20
b=a # b = 10
a=temp

# python一行代码搞定：
a, b = b, a
print(a,b)

链式赋值

a=7
b=a
c=b
d=c

a = b = c = d = 7
print(a,b,c,d)

解压赋值: 取开头和结尾的几个值

salaries=[33,44,55,66,77]
x=salaries[0]
y=salaries[1]
z=salaries[2]
a=salaries[3]
b=salaries[4]

左边变量名的个数与右面包含值的个数相同，多一个不行，少一个也不行

x,y,z,a,b=salaries
print(x,y,z,a,b)

salaries=[33,44,55,66,77,88,99]
x,y,z,*abc=salaries

x,y,z会对应列表salaries的前三个值
然后*会把剩余的值存放一个列表，然后赋值给abc

print(x,y,z)
print(abc)

_当变量名，代表该变量值是无用的

x,y,z,*_=salaries  #取前三个值
print(x,y,z)
print(_)

salaries=[33,44,55,66,77,88,99]
*_,m,n=salaries  # 取后两个值
print(_)
print(m,n)

# salaries=[33,44,55,66,77,88,99]
x,y,z,*_,m=salaries #取后两个值
print(x,y,z)
print(m)

d={'a':1,'b':2,'c':3}
x,y,z=d
print(x,y,z)