call different method with the same name, parameters and return value, select which one is called using const symbol

#include <iostream>

using namespace std;

 

class XY
{
public:
 void show() const
 { cout<<"1"<<endl; }

 

 

 void show()
 { cout<<"2"<<endl; }

};

 

int main()
{

 const XY * const show_1  = NULL;
 show_1->show();

 

 

 XY * show_2 = NULL;
 show_2->show();

}