import math
a=[1,2,3]
b=[1,4,5]
c=a+b
print(c) #[1, 2, 3, 1, 4, 5]
c.sort()
print(c) [1, 1, 2, 3, 4, 5]
c.sort(reverse=False)
print(c) #[1, 1, 2, 3, 4, 5]
c.sort(reverse=True)
print(c) #[5, 4, 3, 2, 1, 1]
print("---")
a.extend(b)
print(a) #[1, 2, 3, 1, 4, 5]
print("----")
c=math.floor(5/2) #2
print(type(c)) #int
print(5/2) # 2.5
print(5//2) #商 2
print(6.2/2) #3.1
print(6.2//2) #3.0
print(6/2) #3.0
print(6//2) #3
# / "就表示 浮点数除法，返回浮点结果;" // "表示整数除法。
x = 3.141596257
print(round(x,3)) #只截取小数点后3位的数,3.142
y = 3.0000
print(round(y,3)) #小数点后3位都为0，所以把多余的0去掉,3.0
x = 3.141596257
print("%.5f" %x) #3.14160
print(int(5/2)) #将int(2.5)返回变成2
