C++语言运行结果问题

大佬们，这个为啥拿Dev c++运行一直报错，结果是什么呢？

#include<iostream.h>
using namespace std;
class Myclass

     {   public:

              void setvalue( int val );

              Myclass ( );

              ~Myclass ( );

         private:

               int i;    };

     Myclass::Myclass( )

     {   i=0;

         cout<<"this is a constructor ! i="<<i<<endl;   }

     void  Myclass::setvalue ( int val )

     {  i=val ;

        cout<<"i="<<i<<endl;   }

     Myclass::~Myclass( )

     {  cout<<"this is a destructor! i="<<i<<endl;   }

     int  main( )

     {  int  k;

        Myclass my[3], *p;

        p=my;

        for( k=0 ;k<3;k++)

        {   p->setvalue (k+1);

            p++;   

         }

                    }

回答：头文件.h去掉，运行截图如下：

#include<iostream>
using namespace std;
class Myclass
{
public:
    void setvalue(int val);
    Myclass();
    ~Myclass();
private:
    int i;
};
Myclass::Myclass()
{
    i = 0;
    cout << "this is a constructor ! i=" << i << endl;
}
void  Myclass::setvalue(int val)
{
    i = val;
    cout << "i=" << i << endl;
}
Myclass::~Myclass()
{
    cout << "this is a destructor! i=" << i << endl;
}
int  main()
{
    int  k;
    Myclass my[3], * p;
    p = my;
    for (k = 0; k < 3; k++)
    {
        p->setvalue(k + 1);
        p++;
    }
}

报的什么错呀