小弟有一个C++的问题请指教一下啊！

[laluji]

#include <iostream.h>
#include <stdio.h>
class Base
{
public:
virtual Base* afn()
{
cout<<"This is Base class. \n";
return this;
}
};
class SubClass:public Base
{
public:
virtual SubClass* afn()
{
cout<<"This is SubClass. \n";
return this;
}
};
void test(Base& x)
{
Base* b;
b=x.afn();
}
void main()
{
Base bc;
SubClass sc;
test(bc);
test(sc);
cin.get();
}
帮我看看哪里有错误啊，我找不到啊，谢谢！

[sunman1982]

#include <iostream>//****************
#include <stdio.h>

using namespace std;//********************
class Base
{
public:
virtual Base* afn()
{
cout<<"This is Base class. \n";
return this;
}
};
class SubClass:public Base
{
public:
virtual SubClass* afn()
{
cout<<"This is SubClass. \n";
return this;
}
};
void test(Base& x)
{
Base* b;
b=x.afn();
}
int main()
{
Base bc;
SubClass sc;
test(bc);
test(sc);
cin.get();
}
dev c++顺利完成

[zhousqy]

什么错误？

[jellard]

虚函数的函数名、参数、返回值必须都相同

[zhangsong1238]

在虚函数的继承时要有相同的函数的返回值一样的，
#include <iostream.h>
#include <stdio.h>
class Base
{
public:
virtual Base* afn()
{
cout<<"This is Base class. \n";
return this;
}
};
class SubClass:public Base
{
public:
virtual Base* afn()//这里要把返回类型改为Base就行了
{
cout<<"This is SubClass. \n";
return this;
}
};
void test(Base& x)
{
Base* b;
b=x.afn();
}
void main()
{
Base bc;
SubClass sc;
test(bc);
test(sc);
cin.get();
}