有如下程序:
#include <iostream>
using namespace std;
class Demo
public:
Demo () cout << "default constructor\n";
Demo (const Demo &x) cout << "copy constructor\";
;
Demo userCode(Demo b) Demo c(b);return c;
int main()
Demo a,d;
cout<<"calling userCode()\n";
d=aserCode(
A.;
ret