day3-04 python入门之运算符

一、运算符

1、算数运算符

# // 取整
>>> 9 // 3
3
>>> 9 // 2
4
>>>

# % 取模（取余数）
>>> 9 % 3
0
>>> 9 % 2
1
>>>

# ** 求平方
>>> 2 ** 2
4
>>> 2 ** 3
8

2、赋值运算符

2.1 增量赋值

# +=
a = 1
a += 3  # a = a + 3
print(a)
4

# -=
a = 1
a -= 1  # a = a -1
print(a)
0

# *=
a = 2
a *= 3  # a = a * 3
print(a)
6

# /=
a = 4
a /= 2  # a = a / 2
print(a)
2

2.2 链式赋值

x = y = z = 1
print(x, y, z)
1 1 1

2.3 交叉赋值

a = 1
b = 2
a, b = b, a
print(a, b)
2 1

2.4 解压赋值

l1 = [1, 2, 3, 4, 5, 6]
a, b, c, d, e, f = l1
print(a, b, c, d, e, f)
1 2 3 4 5 6

# 当我们的字母没有数字多呢？
l1 = [1, 2, 3, 4, 5, 6]
a, b, c, d = l1
print(a, b, c, d)  # 报错

Traceback (most recent call last):
  File "G:/python项目/test/test.py", line 2, in <module>
    a, b, c, d = l1
ValueError: too many values to unpack (expected 4)

# 如何解决？在后面添加*_
l1 = [1, 2, 3, 4, 5, 6]
a, b, c, d, *_ = l1
print(a, b, c, d)
1 2 3 4

# 在前面添加*_
l1 = [1, 2, 3, 4, 5, 6]
*_, a, b, c, d = l1
print(a, b, c, d)
3 4 5 6

3 逻辑运算符

与 或 非

and or not

a = 1
b = 2
c = 3

print(a < b and b > c)  # and:如果有一个式子不符合条件，整条式子都为False
print(a > b and b < c)

print(a < b or b < c)   # or:只要有一个式子符合条件，整条式子都为True
print(a > b or b < c)

print(not a < b)  # 取反

print(a < b and b < c or a > c)  # True

print(a > b or b < c and a > c)  # False