【NOTE】Python 3（三）运算符

算数运算符

#!/usr/bin/env python
# coding=utf-8
#算数运算符
a = 100
b = 20
sum = a + b
print("a + b = ", sum)
sum = a - b
print("a - b = ", sum)
sum = a * b
print("a * b = ", sum)
sum = a / b
print("a / b = ", sum) #返回的是一个浮点数

结果：

 

a + b =  120
a - b =  80
a * b =  2000
a / b =  5.0

 

比较运算符

#!/usr/bin/env python
# coding=utf-8
#比较运算符
a = 100
b = 20
value = a > b
print("a > b = ", value)
value = a < b
print("a < b = ", value)
value = a != b
print("a != b = ", value)
value = a == b
print("a == b = ", value)
value = a >= b
print("a >= b = ", value)
value = a <= b
print("a <= b = ", value)

结果：

 

a > b =  True
a < b =  False
a != b =  True
a == b =  False
a >= b =  True
a <= b =  False

 

赋值运算符

逻辑运算符

#!/usr/bin/env python
# coding=utf-8
#逻辑运算符
ret_and = a == 100 and b == 20
ret_or = a == 100 or b == 10
ret_not = not ret_or
print("ret_and = ", ret_and)
print("ret_or = ", ret_or)
print("ret_not = ", ret_not)

结果：

 

ret_and =  True
ret_or =  True
ret_not =  False

 

取余和取商运算符

%：取余

//：取商的整数（如果被除数或除数是浮点数，那么得到的结果也是浮点数）

notes：（之后的代码使用 PyCharm IDE 进行开发）

#!/usr/bin/env python
# coding=utf-8
num = 9 / 2
print(num)
num = 9 % 2  #取余
print(num)
num = 9 // 2 #取商的整数
print(num)

结果：

4.5
1
4

浮点数

>>> 7//2
3
>>> 7.0//2
3.0
>>> 7//2.0
3.0
>>>

if-in 和 if-not-in

#!/usr/bin/env python
# coding=utf-8
name = "shelmean"
if "shel" in name:
    print("yes")
else:
    print("no")
if "shel" not in name:
    print("yes")
else:
    print("no")

结果：

yes
no