取模%公式, Python的特殊性

通用公式:

a % b = a - int(a / b) * b

 

取整:

1. 向下取整 -∞方向 floor(a/b) 取底除法
   Python
   
   
2. 向零取整, 舍弃小数, 截断除法
   C Java Javascript

 

 

 

取模公式通用, 但是因为取整的区别, Python的取模跟其他语言不一样,Python真是怪胎

1. -10 % 3 = -10 - (-10 / 3) * 3 = -10 - (-9) = -1

   

    

    

    

    Python:  -10 / 3 = -4 是向下取整, 而不是截断

   -10 % 3 = -10 - (-10 / 3) * 3 = -10 - (-4) * 3 = 2

    

2. 10 % -3 = 10 - (10 / -3) * -3 = 1

   

    

    

    

   10 % -3 = 10 - (10 / -3) * -3 = 10 - (-4) * -3 = -2

    

3. 10 % -3.5 = 10 - (10 / -3.5) * -3.5 = 10 - (-2) * -3.5 = 3

   Python

   10 % -3.5 = 10 - (10 / -3.5) * -3.5 = 10 - (-3) * -3.5 = 10 - 10.5 = 0.5

    

4. 10 % -3.4 = 10 - (10 / -3.4) * -3.4 = 10 - (-2) * -3.4 = 3.2

   Python

   10 % -3.4 = 10 - (10 / -3.4) * -3.4 = 10 - (-3) * -3.4 = -0.2