Python————赋值运算符

增量赋值
x=10
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)

not > and > or
0、None、空

print(0 and True)

while 条件：
    代码1
    代码2
    代码3

交叉赋值
a = 10
b = 20
print(a, b)
temp = b
b = a
a = temp
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
salaries = [33, 44, 55, 66, 77]
x = salaries[0]
z = salaries[1]
y = salaries[2]
a = salaries[3]
b = salaries[4]
# x, y, z, a, b, = salaries
print(x, y, z, a, b)

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