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 stun = 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()。
A.120
B.16
C.154
D.34