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I'm a noob at this, but it looks like they want to see some form of a singleton pattern. Here's my stab at it.

#include <iostream>

class ABC {

private:
	ABC() {
		std::cout << "ABC";
	}
	
	~ABC() {
		if (m_ABC != NULL)
			delete m_ABC;
	}
	
	
public:
	static void fun() {
		if (m_ABC == NULL) {
			// create an instance of ABC
			m_ABC = new ABC();
		}
	}
	
	
private:
	static ABC *m_ABC = NULL;

};

int main() {
	ABC::fun();
	return 0;
}

I think they are looking for something like a singleton pattern...

#include <iostream>

class ABC {

private:
	ABC() {
		std::cout << "ABC";
	}
	
	~ABC() {
		if (m_ABC != NULL)
			delete m_ABC;
	}
	
	
public:
	static void fun() {
		if (m_ABC == NULL) {
			// create an instance of ABC
			m_ABC = new ABC();
		}
	}
	
	
private:
	static ABC *m_ABC = NULL;

};

int main() {
	ABC::fun();
	return 0;
}

ur code does not compile

Define the function fun() as pure virtual function.

A few solutions are proposed on cpluspluslearning-petert.blogspot.co.uk/2016/06/c-restrict-creation-of-objects.html.
The focus is on the process of creating and deleting objects.

Declare fun() as non static.
Then you can't make a call to fun() just by referring it via class name.
You have to call this function through object only instead of class like :-
ABC a; // statement 1
a.fun(); // statement 2

But as you the constructor is private and you can't make an instance, so
statement 1 would be illegal.

Also, still you could able to do it by using the below piece of code :-
ABC *a; // statement 1
a->fun(); // statement 2

As fun() is not making any reference to "this" object, so the above 2 statements were possible.

To overcome this, access some data from fun() as below :-

class A {

private:
int z;
A() { cout << " Constrcutor got called " << endl; }
~A() { cout << " destructor got called " << endl; }

public:
static void fun() { A aa; } // statement 1
void fun2() { A aa; } // Statement 2
void fun3() { z = 10; A aa; } // Statement 3

};

int main() {
A::fun();
A *a;
a->fun2();
a->fun3();

}

Now statement 3 will give segmentation fault and call to the constructor will be restricted in this way.

Hi jkl,
I have Microsoft hackerrank round today. Can you please help me by telling what were the questions asked when u gave it?