C++ 对虚拟基类析构函数的“未定义引用”
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"undefined reference" to Virtual Base class destructor
提问by noctilux
Possible Duplicate:
What is an undefined reference/unresolved external symbol error and how do I fix it?
I have some experience with Java, and am now doing a C++ course. I wanted to try writing an interface, but I have run into some trouble with destructors which I have not been able to resolve, even with the help on the Internet... Here's my code:
我有一些 Java 经验，现在正在学习 C++ 课程。我想尝试编写一个接口，但我遇到了一些我无法解决的析构函数的问题，即使在互联网上的帮助下......这是我的代码：
class Force {
public:
virtual ~Force();
virtual VECTOR eval(VECTOR x, double t);
};
class InvSquare : public Force {
public:
InvSquare(double A) {
c = A;
}
~InvSquare(){};
VECTOR eval(VECTOR x, double t) { // omitted stuff }
private:
double c;
};
I have tried to declare a virtual destructor for the base class, and a non-virtual one for the derived class, but I get an error saying "undefined reference to `Force::~Force()'". What does it mean, and how can I fix it?
我试图为基类声明一个虚拟析构函数，并为派生类声明一个非虚拟析构函数，但我收到一条错误消息“对`Force::~Force()'的未定义引用”。这是什么意思，我该如何解决？
Forgive me if this is a silly question!
如果这是一个愚蠢的问题，请原谅我！
Thank you very much for your help, noctilux
非常感谢你的帮助，夜光
回答by Mike Seymour
You've declared the destructor, but not defined it. Change the declaration to:
你已经声明了析构函数，但没有定义它。将声明更改为：
virtual ~Force() {}
to define it to do nothing.
定义它什么都不做。
You also want to make all the functions in the abstract interface pure virtual, otherwise they will need to be defined too:
您还希望将抽象接口中的所有函数设为纯 virtual，否则它们也需要定义：
virtual VECTOR eval(VECTOR x, double t) = 0;
