关于构造拷贝函数的使用和析构函数的调用问题，代码和运行结果如下：

#include "stdafx.h"
#include<iostream>
using namespace std;
class Clock{
private:
int H,M,S;
public:
Clock(int h=0,int m=0,int s=0){
H=h,M=m,S=s;
cout<<"constructor:"<<H<<":"<<M<<":"<<S<<endl;
}
~Clock(){
cout<<"destructor:"<<H<<":"<<M<<":"<<S<<endl;
}
Clock(Clock &p){
cout<<"copy constructor,before call:"<<H<<":"<<M<<":"<<S<<endl;
H=p.H;
M=p.M;
S=p.S;
}
void Showtime(){
cout<<H<<":"<<M<<":"<<S<<endl;
}

};
Clock fun(Clock C)
{
return C;
}
int main(){
Clock C1(8,0,0);
Clock C2(9,0,0);
Clock C3(C1);
fun(C2);
Clock C4;
C4=C2;
system("pause");
return 0;


}
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}

为什么未调用C1,C2,C3,C4的析构函数？？？

C/C++ code

int main()
{
   {
      Clock C1(8,0,0);
      Clock C2(9,0,0);
      Clock C3(C1);
      fun(C2);
      Clock C4;
      C4=C2;
      system("pause");
      return 0;

    }//这样试试
}

明显要这样啊：
C/C++ code

int main()
{
    {
        Clock C1(8,0,0);
        Clock C2(9,0,0);
        Clock C3(C1);
        fun(C2);
        Clock C4;
        C4=C2;
    }

    system("pause");

    return 0;
}

因为return之后才调用析构，这时候cout已经收不到了，要想收到，给个花括号，显式让它们出作用域而析构