Question

Suppose I have pointer of type ABC* and another pointer of type XYZ* and both derive from a common parent class.

If I assign XYZ* to ABC* by explicitly casting it, then what would happen if I call

delete abc; // abc is of type XYZ*

will I get any exception or will it work fine?

I have tried the above code and it doesn’t crashes. So can anyone tell me in what cases will delete throw exception/fault/crash etc?

What are the cases in which delet’ing a pointer crashes the program? Will they crash if both of them have custom destructors defined

Edit: Here is my test code which works without any crashes

class ABC
{
public:
    int a;
    int b;
    int c;
};

class XYZ
{
public:
    double a;
    double b;
    double c;
};

int main()
{
    ABC* abc = new ABC();
    XYZ* xyz = (XYZ*)abc;

    delete xyz;

    return 0;
}

P.S: I’m on Windows platform, if that helps.

EDIT2: Okay so after the readings, I change my question to, when will delete’ing a pointer cause a crash (not including the undefined behaviour)?

EDIT3: What will happen when delete is called? Whose destructor will be called?

Answer 1

If XYZ doesn’t derive from ABC then you shouldn’t be casting an object of the former to the latter – whether your delete works or not is immaterial.