运算符

算数运算符

# 标准算数运算
print(1 + 1)  # 加法；2
print(1 - 1)  # 减法；0
print(1 * 2)  # 乘法；2
print(5 / 2)  # 除法；2.5
print(5 // 2)  # 整除；2
print(5 % 2)  # 取余运算；1
print(5 ** 2)  # 幂运算；5的2次方=25

# 整除（一正一负）
print(-5 // 2)  # 整除（一正一负向下取整）；-3
print(5 // -2)  # 整除（一正一负向下取整）；-3
print(-5 // -2)  # 整除（都为正或都为负，则为正）；2

# 取余（一正一负）：余数=被除数-除数*商
print(-5 % 2)  # 取余运算；[(-5)-(2)*(-3)=(-5)+6=1]
print(5 % -2)  # 取余运算；[5-(-2)*(-3)=5-6=-1]
print(-5 % -2)  # 取余运算；都为正或负，余数前加对应正负号 -1

赋值运算符

a = 20
b = 20
c = 20

# 支持链式赋值
# 链式赋值的变量指向同一个内存地址
a2 = b2 = c2 = 20
print(a2, id(a2))
print(b2, id(b2))
print(c2, id(c2))

# 支持参数赋值
parm = 20
parm += 20
print(parm)
parm -= 20
print(parm)
parm *= 30
print(parm)
parm /= 10
print(parm)

# 支持系列解包赋值
x, y, z = 10, 20, 30
print(x, y, z)

# 交换两个变量的值
temp1, temp2 = 10, 20
print('交换之前：', temp1, temp2)
# 开始交换
temp1, temp2 = temp2, temp1
print('交换之后：', temp1, temp2)

比较运算符

a, b = 10, 20
print(a > b)
print(a < b)
print(a <= b)
print(a >= b)
print(a == b)
print(a != b)

"""
一个变量由三部分组成：标识，类型，值
== 符号比较对象的值
is/is not 符号比较对象的标识
"""

a = 10
b = 10
print(a == b)  # True；值相等
print(a is b)  # True；标识相等
print(a is not b)  # False；标识相等

list1 = [11, 22, 33, 44]
list2 = [11, 22, 33, 44]
print(list1 == list2)  # True；值相等
print(list1 is list2)  # False；标识不相等
print(list1 is not list2)  # True；标识不相等

布尔运算符

a, b = 1, 2
print(a == 1 and b == 2)  # True
print(a == 1 and b != 2)  # False
print(a != 1 and b == 2)  # False
print(a != 1 and b != 2)  # False

print(a == 1 or b == 2)  # True
print(a == 1 or b != 2)  # True
print(a != 1 or b == 2)  # True
print(a != 1 or b != 2)  # False

print(not True)  # False
print(not False)  # True

str_content = '123456'
print('1' in str_content)  # True
print('9' in str_content)  # False

print('1' not in str_content)  # False
print('9' not in str_content)  # True

位运算符

# 按位与；同为1时结果为1
print(4 & 8)  # 0

# 按位或；同为0时结果为0
print(4 | 8)  # 12

# 左移位；相当于乘以2
print(4 << 1)  # 8
print(4 << 2)  # 16
# 右移位；相当于除以2
print(4 >> 1)  # 2
print(4 >> 2)  # 1