基本运算符
1、算术运算符
2、比较运算符
name = 'stone'
print(name=='stone')
print(name!='stone')
True
False
list1=[1,'b',8,9]
list=[8]
list2=[8,'a']
list3=[1,7]。
print(list<list1) #列表比较大小仅限于同一位置所对应的值是相同的类型
print(list1<list2) #列表比较大小仅限于同一位置所对应的值是相同的类型
print(list1<list3) #列表比较大小仅限于同一位置所对应的值是相同的类型
False
True
Traceback (most recent call last):
File "D:/Program Files/JetBrains/python学习/day 12/1.py", line 27, in <module>
print(list1<list3)
TypeError: '<' not supported between instances of 'str' and 'int'
3、赋值运算符
age= 24
age+=1
print(age)
25
number= 24
number*=10
print(number)
240
4、逻辑运算符
print(3 > 3 and 1 > 2 or 2 > 1)
True
5、身份运算符
is和= =的区别:is用于判断两个变量引用对象是否为同一个(是否在同一快内存空间中),==用于判断引用变量的值是否相等。
x = 256
y = x
z = 256
print(id(x))
print(id(y))
print(id(z))
print(f'x is y:{x is y}')
print(f'x == y:{x==y}')
print(f'x is z:{x is z}')
print(f'x == z:{x==z}')
1416393808
1416393808
1416393808
x is y:True
x == y:True
x is z:True
x == z:True
id相同的,值一定相同,值相同的id不一定相同,除了小整数池的除外。
6、成员运算符
7、运算符优先级
8、链式赋值(重要)
a = 15
b = 15
c = 15
d = 15
print(f'a:{a}, b:{b}, c:{c}, d:{d}')
a:15, b:15, c:15, d:15
a = b = c = d =15
print(f'a:{a}, b:{b}, c:{c}, d:{d}')
a:15, b:15, c:15, d:15
9、交叉赋值(重要)
x = 100
y = 180
temp = x
x = y
y = temp
print(f'x:{x}')
print(f'y:{y}')
x:180
y:100
x = 100
y = 180
x,y = y,x
print(f'x:{x}')
print(f'y:{y}')
x:180
y:100
10、解压缩(重要)
name_list = ['nick', 'egon', 'jason']
x = name_list[0]
y = name_list[1]
z = name_list[2]
print(f'x:{x}, y:{y}, z:{z}')
x:nick, y:egon, z:jason
解压缩其实就是解包把多个商品一次性拿出来。
name_list = ['nick', 'egon', 'jason']
x,y,z = name_list
print(f'x:{x},y:{y},z:{z}')
x:nick,y:egon,z:jason
有时候我们解压缩的值可能是我们不想要的,那么可以使用下划线,万能的下划线。
name_list = ['nick', 'egon', 'jason', 'tank']
x, _, z, _ = name_list
print(f'x:{x},y:{y},z:{z},a:{a}')
Traceback (most recent call last):
File "D:/Program Files/JetBrains/python学习/day 12/1.py", line 71, in <module>
print(f'x:{x},y:{y},z:{z},a:{a}')
NameError: name 'y' is not defined
name_list = ['nick', 'egon', 'jason', 'tank', 'kevin', 'jerry']
x, y, *_, z = name_list
print(f'_:{_}')
_:['jason', 'tank', 'kevin']
python追求的是简洁性,代码不要写的太长了。因此字典也是可以的,但是字典解压缩的是key。
info = {'name':'stone','age':18}
x ,y =info
print(x,y)
name age