#include <iostream>
using namespace std;
double power(double a, int b)
{
double result=1;
while (b--)
result *= a;
return result;
}
int main()
{
cout<<power(3, 2);
}
```
```cpp
#include <iostream>
using namespace std;
double power(double a, int b)
{
double result=1;
while (--b)
result *= a;
return result;
}
int main()
{
cout<<power(3, 2);
}
```
第一个程序结果是9 第二个是3!