Question

在项目中，我有一个虚拟课程：

class Base {
public:
    Base();
    virtual void insert(const Node& n);
    virtual Node extract_min() = 0;
    virtual int size() = 0;
    virtual ~Base() {};
};

我派出了班级：

class Derived: public Base {
public:
    derived(int MaxN = MAXN);

    void insert(const Node& n);
    Node extract_min();
    int size() {
        return cnt;
    }

    virtual ~Derived();
};

及其构造函数：

Derived::Derived(int MaxN): Base() {
    //something happes here;
}

它的析构函数：

Derived::~Derived() {
    free(my_array);
}

但是当我做到这一点时，我一直在链接阶段出现这个错误：

obj/Derived.o: In function `Derived::~Derived()':
Derived.cpp:(.text+0x160): undefined reference to `vtable for Base'
obj/Derived.o: In function `Derived::Derived(int)':
Derived.cpp:(.text+0x199): undefined reference to `Base::Base()'
Derived.cpp:(.text+0x516): undefined reference to `vtable for Base'

有人知道如何修复它吗？

Answer 1

undefined reference to `vtable for Base'

此错误表示您忘记在Base类中提供（不纯）虚拟函数的定义。从其他错误看，你似乎错过了所有成员的定义。

Answer 2

您应该为基类添加ctor的定义。这可以解决链接错误。

class Base {
public:
    Base{};
    virtual void insert(const Node& n);
    virtual Node extract_min() = 0;
    virtual int size() = 0;
    virtual ~Base() {};
};

此外，您还添加了在派生类

中继承的虚函数的定义

从虚拟类派生

2 个答案: