知道错在哪里，但不知道什么错

[陈思有]

#include <iostream>

class Mammal
{
public:
	Mammal():age(1) { std::cout << "Mammal construct\n";  }
	virtual ~Mammal() { std::cout << "Mammal destruct\n";  }
	virtual void speak() const { std::cout << "Mammal speak\n";  }
protected:
	int age;
};

class Cat: public Mammal
{
public:
	Cat() { std::cout << "Cat constructor\n"; }
	~Cat() { std::cout << "Cat destructor\n"; }
	void speak() const { std::cout << "Meow!\n"; }
	void purr() const { std::cout << "Rrrrrrrr\n"; }
};

class Dog: public Mammal
{
public:
	Dog() { std::cout << "Dog constructor\n";  }
	~Dog() { std::cout << "Dof destructor\n"; }
	void speak() const { std::cout << "Woof\n"; }
};

int main()
{
	const int numberMammals = 3;
	Mammal* zoo[numberMammals];
	Mammal* pMammal;
	int choice,i;
	
	for (i = 0; i < numberMammals; i++)
	{
		std::cout << "(1)Dog (2)Cat: ";
		std::cin >> choice;
		if(choice == 1)
			zoo[i] = new Dog;
		else
			zoo[i] = new Cat;

		
	}

	std::cout << "\n";

	for (i=0; i < numberMammals; i++)
	{
		zoo[i]->speak();

	Cat *pRealCat = dynamic_cast<Cat *> (zoo[i]); //问题出在这里，但是我是按书上的，？？？
		if (pRealCat)
			pRealCat->purr(); 
		else
			std::cout << "Uh oh, not a cat!\n";    

		delete zoo[i];
		std::cout << "\n";
	}
 
	return 0;
}

[陈思有]

实在吃力

[陈思有]

原来要对VC6.0进行设置，但为什么要设置呢？

[ProgrammingRing]

不会C++啊。。不是有个C++区嘛？

[qq120848369]

(1)Dog (2)Cat: 1
Mammal construct
Dog constructor
(1)Dog (2)Cat: 2
Mammal construct
Cat constructor
(1)Dog (2)Cat: 1
Mammal construct
Dog constructor

Woof
Uh oh, not a cat!
Dof destructor
Mammal destruct

Meow!
Rrrrrrrr
Cat destructor
Mammal destruct

Woof
Uh oh, not a cat!
Dof destructor
Mammal destruct

[陈思有]

[Quote=引用 3 楼 programmingring 的回复:]
不会C++啊。。不是有个C++区嘛？
[/Quote]
以前都是来C语言区，所以不知不觉就……

[notitle1102]

我的理解是，在类层次间进行下行转换时，dynamic_cast会类型检查，Cat *pRealCat = dynamic_cast<Cat *> (zoo[i])是要把Mammal类型的指针转换成Cat类型，dynamic_cast执行失败，因为Cat的一些属性Mammal没有。一个解决办法是把dynamic_cast用static_cast代替，因为static_cast不会类型检查（不过存在不安全因素）

[Roy_Smiling]

vs2008 完全没有错！不知道楼主的是什么错。

[Song9007206710328]

不可由基类对子类进行dynamic_cast,具体参见MSDN中的dynamic_cast