Python运算符

1：算术运算符

+:加       两个对象相加 a + b

-:减       得到负数或是一个数减去另一个数

*:乘       两个数相乘或是返回一个被重复若干次的字符串

/:除       x除以y

%:取模     返回除法的余数

**:幂      返回x的y次幂 

//:取整除   返回商的整数部分

a = 21
b = 10
c = 0

c = a + b
print("a = ", a, "b = ", b, "a+b = ", c)

c = a - b
print("a = ", a, "b = ", b, "a-b = ", c)

c = a * b
print("a = ", a, "b = ", b, "a*b = ", c)

c = a / b
print("a = ", a, "b = ", b, "a/b = ", c)

c = a % b
print("a = ", a, "b = ", b, "a%b = ", c)

a = 2
b = 3
c = a ** b
print("a = ", a, "b = ", b, "a**b = ", c)

a = 9
b = 4
c = a // b
print("a = ", a, "b = ", b, "a//b = ", c)


print("1" + "2")

print([1, 2] + [3, 4])

输出结果为

a = 21 b = 10 a+b = 31
a = 21 b = 10 a-b = 11
a = 21 b = 10 a*b = 210
a = 21 b = 10 a/b = 2.1
a = 21 b = 10 a%b = 1
a = 2 b = 3 a**b = 8
a = 9 b = 4 a//b = 2
12
[1, 2, 3, 4]

2：赋值运算符

=:   简单的赋值运算符   c = a + b 将 a + b 的运算结果赋值为 c
+=:  加法赋值运算符     c += a 等效于 c = c + a
-=:  减法赋值运算符     c -= a 等效于 c = c - a
*=:  乘法赋值运算符     c *= a 等效于 c = c * a
/=:  除法赋值运算符     c /= a 等效于 c = c / a
%=:  取模赋值运算符     c %= a 等效于 c = c % a
**=: 幂赋值运算符       c **= a 等效于 c = c ** a
//=: 取整除赋值运算符    c //= a 等效于 c = c // a

a = 21
b = 10
c = 0

# 赋值运算符
c = a + b
print("c = ", c)

# 加法赋值运算符
c += a
print("c = ", c)

# 减法赋值运算符
c -= a
print("c = ", c)

# 乘法赋值运算符
c *= a
print("c = ", c)

# 除法赋值运算符
c /= a
print("c = ", c)

# 取模赋值运算符
c = 2
c %= a
print("c = ", c)

# 幂赋值运算符
a = 3
c **= a
print("c = ", c)

# 取整除赋值运算符
c //= a
print("c = ", c)

输出结果为

c = 31
c = 52
c = 31
c = 651
c = 31.0
c = 2
c = 8
c = 2

3：比较运算符

==: 等于         比较对象是否相等  (a == b) 
!=: 不等于       比较两个对象是否不相等  (a != b) 
<>: 不等于       比较两个对象是否不相等  (a <> b) 这个运算符类似 != 。(python2.x版本支持，python3.x版本支持，为了方便统一使用!=)
>:  大于         返回x是否大于y  (a > b) 
<:  小于         返回x是否小于y。所有比较运算符返回1表示真，返回0表示假。这分别与特殊的变量True和False等价。  (a < b) 
>=: 大于等于      返回x是否大于等于y。  (a >= b) 
<=: 小于等于      返回x是否小于等于y。    (a <= b) 
is: 是判断两个标识符是不是引用自一个对象  x is y, 类似 id(x) == id(y) , 如果引用的是同一个对象则返回 True，否则返回 False


链状比较运算符   例如 10 < a <=66

a = 20
b = 10
c = 0

print("a == b ", a == b)
print("a != b ", a != b)
# print(a <> b) 在python3.x版本下会报错的
print("a > b ", a > b)
print("a < b ", a < b)

b = 20
print("a >= b ", a >= b)
print("a <= b ", a <= b)

# is是比对唯一标识的
print("id(a) = ", id(a))
print("id(b) = ", id(b))
print("a is b ", a is b)

a = [1]
b = [1]
print("a == b ", a == b)
print(" a is b ", a is b)

print("id(a) = ", id(a))
print("id(b) = ", id(b))

a = 20
b = 10
print(10 < a < 25)

输出结果：

a == b False
a != b True
a > b True
a < b False
a >= b True
a <= b True
id(a) = 1535632448
id(b) = 1535632448
a is b True
a == b True
a is b False
id(a) = 5501136
id(b) = 4805976
True

4：逻辑运算符

以下假设变量 a 为 10, b为 20:

and:   x and y   布尔"与" - 如果 x 为 False，x and y 返回 False，否则它返回 y 的计算值。  (a and b) 返回 20。
or:    x or y    布尔"或"    - 如果 x 是非 0，它返回 x 的值，否则它返回 y 的计算值。 (a or b) 返回 10。
not:   not x     布尔"非" - 如果 x 为 True，返回 False 。如果 x 为 False，它返回 True。 not(a and b) 返回 False

b = True
print(not b)


a = False
print(a and b)


print(a or b)


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

print(a or b)

a = 0
print(a or b)


print(not b)

输出结果：

False
False
True
20
10
20
False