Attempt to make singleton class in C++

singleton.cpp

#include<iostream>
using namespace std;

class Singleton
{
private:
	static Singleton obj;
	Singleton(){
		cout<<"Constructor does not get called";
	}
	string s;
public:
	
	int get_value()
    {
        cout<<"It works";
    }
	static Singleton getInstance()
	{
		if(&obj == NULL)
			Singleton* obj = new Singleton;
		return obj;
	}
};

Singleton Singleton::obj; 

int main()
{
	Singleton::getInstance().get_value();

	return 0;
}