prog4.cpp

C++语言程序设计题典

#include <iostream.h>
class A
{
public:
	int va;
	A(int i) { va=i; }
	virtual A& operator+(A&);
	virtual A& operator=(A&);
	virtual int a() { return va; }
	virtual int b() { return 0; }
	virtual int c() { return 0; }
	void disp() { cout << "va=" << va << endl; }
};
class B : public A
{
public:
	int vb;
	B(int i,int j) : A(i) { vb=j; }
	virtual A& operator+ (A&);
	virtual A& operator= (A&);
	virtual int b() { return vb; }
	void disp() { cout << "vb=" << vb << endl; }
};
class C : public B
{
public:
	int vc;
	C(int i,int j,int k) : B(i,j) { vc=k; }
	virtual A& operator+ (A&);
	virtual A& operator= (A&);
	virtual int c() { return vc; }
	void disp() { cout << "vc=" << vc << endl; }
};
A& A::operator+(A& t)
{
	va+=t.a();
	return *this;
}
A& A::operator=(A& t)
{
	va=t.a();
	return *this;
}
A & B::operator+(A& t)
{
	va+=t.a();
	vb+=t.b();
	return *this;
}
A & B::operator=(A& t)
{
	va=t.a();
	vb=t.b();
	return *this;
}
A& C::operator+(A& t)
{
	va+=t.a();
	vb+=t.b();
	vc+=t.c();
	return *this;
}
A& C::operator=(A& t)
{
	va=t.a();
	vb=t.b();
	vc=t.c();
	return *this;
}
void addobject(A& ob1,A& ob2)
{
	ob1=ob1+ob2;
}
void main()
{
	A a(10);
	B b(10,20);
	C c(10,20,30);
	addobject(a,b);
	addobject(b,c);
	addobject(c,b);
	a=b+c;
	c=c+a;
	a.disp();
	b.disp();
	c.disp();
}