python计算结果显示小数

先将整型转换成float型，在计算，结果就有小数了

>>> a = 10
>>> b = 4
>>> c = a/b
>>> a,b,c
(10, 4, 2)
>>> a = float(a)
>>> d = a/b
>>> a,b,d
(10.0, 4, 2.5)
>>>