看看这个错误是怎么改？

[flydream1980]

http://www.cnblogs.com/chio/archive/2007/11/24/970983.html
这篇文章里的这个例子，我这怎么编译出错，是不是编译器的问题？代码如下

#include <iostream>
using namespace std; 
class Base1
{
public:    
	Base1()
	{
		cout << "Base1::Base1()" << endl;
	}   
	virtual ~Base1()
	{
		cout << "Base1::~Base1()" << endl;
	}   
	virtual void speakClearly()
	{
		cout << "Base1::speakClearly()" << endl;
	}   
	virtual Base1 *clone() const
	{ 
		cout << "Base1::clone()" << endl;
	}
protected:
    float data_Base1;
};
class Base2
{
public:   
	 Base2()
	 { 
		 cout << "Base2::Base2()" << endl;
	 }   
	 virtual ~Base2()
	 { 
		 cout << "Base2::~Base2()" << endl;
	 }  
	 virtual void mumble()
	 { 
		 cout << "Base2::mumble()" << endl;
	 }   
	 virtual Base2 *clone() const
	 { 
		 cout << "Base2::clone()" << endl;
	 }
protected:
	 float data_Base2;
}; 
class Derived : public Base1, public Base2
{
public:   
	Derived()
	{
		cout << "Derived::Derived()" << endl;
	}   
	virtual ~Derived()
	{
		cout << "Derived::~Derived()" << endl;
	}   
	virtual Derived *clone() const 
	{ 
		cout << "Derived::clone()" << endl;
	}
protected:  
	float data_Derived;
}; 
int main()
{
	
	Base1 *pBase1=new Derived;  
	pBase1->clone();  
	pBase1->speakClearly();  
	//pBase1->mumble();//complie-time error   
	delete pBase1;   
	cout << "-----------------------------------" << endl;   
	Base2 *pBase2=new Derived;  
	pBase2->clone();   
	pBase2->mumble();   
	delete pBase2;    
	system("PAUSE");   
	return 0;
	
}

错误如下
error C2555: 'Derived::clone' :overriding virtual function differs from 'Base1::clone' only by return type or calling convention
error C2555: 'Derived::clone' : overriding virtual function differs from 'Base2::clone' only by return type or calling convention

[xiaoyisnail]

gcc编译通过，这个是vc6支持不好的原因

[星羽]

你的几个clone没返回值

#include "stdafx.h"

#include <iostream>
using namespace std; 
class Base1
{
public:    
    Base1()
    {
        cout << "Base1::Base1()" << endl;
    }   
    virtual ~Base1()
    {
        cout << "Base1::~Base1()" << endl;
    }   
    virtual void speakClearly()
    {
        cout << "Base1::speakClearly()" << endl;
    }   
    virtual Base1 *clone() const
    { 
        cout << "Base1::clone()" << endl;
        return NULL;
    }
protected:
    float data_Base1;
};
class Base2
{
public:   
    Base2()
    { 
        cout << "Base2::Base2()" << endl;
    }   
    virtual ~Base2()
    { 
        cout << "Base2::~Base2()" << endl;
    }  
    virtual void mumble()
    { 
        cout << "Base2::mumble()" << endl;
    }   
    virtual Base2 *clone() const
    { 
        cout << "Base2::clone()" << endl;
        return NULL;
    }
protected:
    float data_Base2;
}; 
class Derived : public Base1, public Base2
{
public:   
    Derived()
    {
        cout << "Derived::Derived()" << endl;
    }   
    virtual ~Derived()
    {
        cout << "Derived::~Derived()" << endl;
    }   
    virtual Derived *clone() const 
    { 
        cout << "Derived::clone()" << endl;
        return NULL;
    }
protected:  
    float data_Derived;
}; 
int main()
{

    Base1 *pBase1=new Derived;  
    pBase1->clone();  
    pBase1->speakClearly();  
    //pBase1->mumble();//complie-time error   
    delete pBase1;   
    cout << "-----------------------------------" << endl;   
    Base2 *pBase2=new Derived;  
    pBase2->clone();   
    pBase2->mumble();   
    delete pBase2;    
    system("PAUSE");   
    return 0;

}

[xiaoyisnail]

标准允许子类重写的虚函数的返回类型为父类中相应虚函数返回类型的继承层次下的类型

[lq20051610211]

用多继承时得注意看返回值类型~

[iGoo]

函数clone内没有返回值

[hai040]

改错的话很简单
去掉derived里的clone，再如ls说的加上返回值

原因不清楚，单继承是可以的，不知道为什么多继承会出错

[flydream1980]

http://www.cnblogs.com/chio/archive/2007/11/24/970983.html
呵呵，原文的程序有错误？ 还是编译器不同造成的

[ckt]

vs的话改成下面就可以了, vc6.0的话编译不过

#include <iostream>
using namespace std; 
class Base1
{
public:    
	Base1()
	{
		cout << "Base1::Base1()" << endl;
	}   
	virtual ~Base1()
	{
		cout << "Base1::~Base1()" << endl;
	}   
	virtual void speakClearly()
	{
		cout << "Base1::speakClearly()" << endl;
	}   
	virtual Base1 *clone() const
	{ 
		cout << "Base1::clone()" << endl;
		return (Base1*)this;
	}
protected:
	float data_Base1;
};

class Base2
{
public:   
	Base2()
	{ 
		cout << "Base2::Base2()" << endl;
	}   
	virtual ~Base2()
	{ 
		cout << "Base2::~Base2()" << endl;
	}  
	virtual void mumble()
	{ 
		cout << "Base2::mumble()" << endl;
	}   
	virtual Base2 *clone() const
	{ 
		cout << "Base2::clone()" << endl;
		return (Base2 *)this;
	}
protected:
	float data_Base2;
}; 

class Derived : public Base1, public Base2
{
public:   
	Derived()
	{
		cout << "Derived::Derived()" << endl;
	}   
	virtual ~Derived()
	{
		cout << "Derived::~Derived()" << endl;
	}   
	virtual Derived *clone() const 
	{ 
		cout << "Derived::clone()" << endl;
		return (Derived*)this;
	}
protected:  
	float data_Derived;
}; 

[nullah]

楼上的该法
VS2005可以编译运行通过

没试过其它编译器
至少函数没返回值是错误的吧

[qingkongyihe2008]

加上返回值

[hai040]

vc7编译不过...
那是编译器问题了

[xdfd]

dev-c++通过!

[sagegz]

加上返回值就可以了,很多时候错误跟编译器有关系.

[hityct1]

vc9.0也编译不过

[帅得不敢出门]

返回值的原因
icc
0 error(s), 4 warning(s)
可以编译通过。

[waizqfor]

mark!~~

[kaidiligent0]

我来学习了.哈哈.