有如下程序：
#include <iostream>
using namespace std;
class Sample
{
friend long fun(Sample s);
public:
Sample(long a ) {x=a;}
private:
long x;
};
long fun(Sample s)
{
if(s.x<2)
return 1;
return s.x*fun(Sample(s.x -1));
}
int main()
{
int sum=0;
for(int i=0;i<6;i++){sum+=fun(Sample(i));}
cout<<sum;
return 0;
}
运行时输出的结果是