【测试开发】python系列教程：Python 运算符

>>> 4+5
9
>>>

算术运算符
比较（关系）运算符
赋值运算符
逻辑运算符
位运算符
成员运算符
身份运算符
运算符优先级

>>> 5+6
11

>>> 6-5
1

>>> 4*5
20

>>> 10/2
5.0

>>> 3%2
1

>>> 3**2
9

>>> 8//3
2

>>> 3==2
False

>>> 3!=2
True

>>> 3>2
True

>>> 3<2
False

>>> 3>=2
True

>>> 3<=2
False

>>> c=1+2
>>> c
3

>>> c+=1
>>> c
4

>>> c-=2
>>> c
2

>>> c*=2
>>> c
4

>>> c/=2
>>> c
2.0

>>> c%=2
>>> c
0.0

>>> c=10
>>> c**=8
>>> c
100000000

>>> c//13
7692307

>>> 10 and 20
20

>>> 10 or 20
10

>>> not ( 1==2)
True

>>> a=[1,2,3]
>>> 1 in  a
True

>>> 1 not in  a
False

>>> a=10
>>> b=200
>>> a is b
False

>>> not (a is b)
True

注：
is 与 == 区别：
  is 用于判断两个变量引用对象是否为同一个， 
  == 用于判断引用变量的值是否相等

a = 20
b = 10
c = 15
d = 5
e = 0
e = (a + b) * c / d       #( 30 * 15 ) / 5
print ("(a + b) * c / d 运算结果为：",  e)
 
e = ((a + b) * c) / d     # (30 * 15 ) / 5
print ("((a + b) * c) / d 运算结果为：",  e)
 
e = (a + b) * (c / d)    # (30) * (15/5)
print ("(a + b) * (c / d) 运算结果为：",  e)
e = a + (b * c) / d      #  20 + (150/5)
print ("a + (b * c) / d 运算结果为：",  e)

(a + b) * c / d 运算结果为：90.0
((a + b) * c) / d 运算结果为：90.0
(a + b) * (c / d) 运算结果为：90.0
a + (b * c) / d 运算结果为：50.0