数值的整数次方

class Solution {
public:
double Power(double base, int exponent) {
if (exponent == 0)
return 1;
else if (exponent > 0)
{

double sum = 1;
for (int i = 0 ; i < exponent ;++i)
{
sum = sum*base;
}
return sum;
}
else
{
exponent = -1 * exponent;
double sum = 1;
for (int i = 0 ; i < exponent ;++i)
{
sum = sum/base;
}
return sum;
}
}
};