A question about virtual function

[ningfan666]

Hello I have a question about virtual function.
I have a base class and a derived class below:

class Person
{
public:
	virtual void eat() = 0;
};

class Student : public Person
{
public:
        Student()
	{
		memset(this, 0, sizeof(Student));
	}
	void eat()override;
};
void Student::eat()
{
	std::cout << "eat breakfast...\n";
}

And I have a main function:

int main()
{
	Student s1;
	s1.eat();
	return EXIT_SUCCESS;
}

I ran this program in VS2022 and when s1's default constructor was called.Its _vfptr was set to 0x0000...
I thought that s1 must call virtual function eat() via its _vfptr and I set its value as 0.But it could still call eat() correctly.I don't know why this happens.Could someone tell me the reason please? Thank you very much!

[JLBorges]

memset(this, 0, sizeof(Student)); engenders undefined behaviour (Student is not a TriviallyCopyable type).

In s1.eat() there is no virtual call (the function is not called through a pointer or reference); evaluated as s1.Student::eat().

[ningfan666]

Thank you so much！I get it.