A little knowledge ~ miscellaneous notes on topics ~ a polymorphic problem

Question code

class A
{
    
public:
	virtual void func(int val = 1){
     std::cout << "A->" << val << std::endl; }
	virtual void test(){
     func(); }
};
class B : public A
{
    
public:
	void func(int val = 0){
     std::cout << "B->" << val << std::endl; }
};
int main(int argc, char* argv[])
{
    
	B* p = new B;
	p->test();
	p->func();
	return 0;
}

Running results ：

explain ：

The rewritten virtual function of a subclass will overwrite the corresponding virtual function pointer of the corresponding virtual function of the parent class in its virtual table , The virtual table is in the code segment , But in the parent class of the call at this time test() when , Its val The value of is 1, So this problem will first call the corresponding virtual function pointer in the subclass virtual table , Execute the virtual function , But the invoked val It will also be the value saved by the parent class in the stack ！！！！