My setter doesn't work in new class (inheritance) - c++

Question

This is my code. I created base class and in constructor set x=0. Next I used virtual set_x() = 0. And I created set_x() in new class. Output:
set x
100
DONE. Let's check. 0500
Why I got 0500 not 100500?
#include "mainwindow.h"
#include <QApplication>
#include <fstream>
#include <string>
#include <iostream>
using namespace std;
struct invalid_file_handler : std::runtime_error{
using runtime_error::runtime_error;
};
class base_class{
private:
int x;
int y;
public:
virtual void set_x()=0;
void set_y(){
this->y=500;
}
int get_x(){
return (this->x);
}
int get_y(){
return (this->y);
}
base_class(){
this->x=0;
this->y=0;
}
};
class new_class :public base_class{
public:
void set_x();
private:
int z;
int x;
int y;
};
void new_class::set_x(){
cout << "set x " << endl;
this->x=100;
cout << this->x << endl << "DONE. Let's check. ";
}
int main()
{
ifstream my_open_file;
string file_path = "/home/wojtek/Pulpit/elo.odt";
try{
my_open_file.open("/home/wojtek/Pulpit/elo.odt");
my_open_file.close();
}catch (std::runtime_error &e){
cerr << "Hello Xd XD chua" << endl;
cerr << e.what();
}
ofstream myfile;
try{
myfile.open ("/home/wojtek/Pulpit/example.txt");
myfile << "Writing this to a file.\n";
myfile.close();
}
catch(invalid_file_handler &e){
cerr << "Hello!" << endl;
}
new_class *object = new new_class();
object->set_x();
cout << object->get_x();
object->set_y();
cout << object->get_y();
//base_class object;
//cout << object.get_y();
return 0;
}

Answer 1

The variables x and y declared in new_class are shadowing the variables with the same names declared in base_class. This means that in any member method of new_class, the name x refers to new_class::x and not base_class::x.
Simply remove these lines from the new_class definition:
int x;
int y;
And make the same members in the base_class protected instead of private so that the new_class also has access:
class base_class{
protected:
int x;
int y;
Note: your code has a memory leak, since you never delete object after allocating it. Always delete what you new, and don't use new unless you really need to.