需要考虑的几种情况在代码中标明

class Solution:
    def Power(self, base, exponent):
        # write code here
        temp = base
        # 0的0次方和0的负数次方无意义
        if base == 0.0 and exponent <= 0:
            return None
        #0的次方为0
        if base == 0.0 :
            return 0
        #除0以外的任何数的0次方都为0
        if exponent == 0:
            return 1
        #负数次方时
        if exponent < 0:
            for i in range(-exponent-1):
                base *= temp
            return 1.0 / base
        else:
            #正数次方时
            for i in range(exponent-1):
                base *= temp
            return base