打印虚拟成员函数的地址 [英] print address of virtual member function

问题描述

我正在尝试打印虚拟成员函数的地址。
如果我只想打印函数的地址，我可以写：

I am trying to print the address of a virtual member function. If I only wants to print the address of the function I can write:

print("address: %p", &A::func);

但我想这样做：

A *b = new B();

printf("address: %p", &b->func); 
printf("address: %p", &b->A::func);

然而这不编译，是可能做这样的事情甚至做
vb中的地址是否在运行时完成？

however this does not compile, is it possible to do something like this even do looking up the address in the vtable is done in runtime?

推荐答案

此代码是否打印正确的地址？它将在vtable中打印函数的地址，但是是正确的：）

Will this code print the right address? It will print the address of the function in the vtable, but is it correct:)?

struct A
{
    virtual void func() { cout << "A::func" << endl; }
};

struct B : public A
{
    void func() { cout << "B::func" << endl; }
};

typedef void (*functionPtr)();

int main()
{
    A *b = new B();

    int *vptr = *(int**)&b;
    int *vtable = (int *)*vptr; 

    functionPtr fp = (functionPtr)vtable[0];

    printf("address A::func = %p\n", fp);

    return 0;
}

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