#include <iostream>
using namespace std;
class A
{
public:
A()
{
cout<<"Constructor called:A"<<endl;
}
};
class B:public A
{
public:
B()
{
cout<<"Constructor called:B"<<endl;
}
};
class C:public A
{
public:
C()
{
cout<<"Constructor called:C"<<endl;
}
};
class D:public B,public C
{
public:
D()
{
cout<<"Constructor called:D"<<endl;
}
};
int main()
{
D objd;
return 0;
} 
#include <iostream>
using namespace std;
class A
{
public:
A()
{
cout<<"Constructor called:A"<<endl;
}
};
class B:virtual public A
{
public:
B()
{
cout<<"Constructor called:B"<<endl;
}
};
class C:public A
{
public:
C()
{
cout<<"Constructor called:C"<<endl;
}
};
class D:public B,public C
{
public:
D()
{
cout<<"Constructor called:D"<<endl;
}
};
int main()
{
D objd;
return 0;
}
结果：A B A C D
#include <iostream>
using namespace std;
class A
{
public:
A()
{
cout<<"Constructor called:A"<<endl;
}
};
class B:virtual public A
{
public:
B()
{
cout<<"Constructor called:B"<<endl;
}
};
class C:virtual public A
{
public:
C()
{
cout<<"Constructor called:C"<<endl;
}
};
class D:public B,public C
{
public:
D()
{
cout<<"Constructor called:D"<<endl;
}
};
int main()
{
D objd;
return 0;
}
结果：A B C D
#include <iostream>
using namespace std;
class A
{
public:
A()
{
cout<<"Constructor called:A"<<endl;
}
};
class B:public A
{
public:
B()
{
cout<<"Constructor called:B"<<endl;
}
};
class C:virtual public A
{
public:
C()
{
cout<<"Constructor called:C"<<endl;
}
};
class D:public B,public C
{
public:
D()
{
cout<<"Constructor called:D"<<endl;
}
};
int main()
{
D objd;
return 0;
}
结果：AABCD