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Interview Questions on Singletone Classes in C++ : 2

Question: 1

//find the output of below code on Singleton class

#include <iostream>

class Singleton
{
    private:
        static Singleton* instance;
        Singleton();

    public:
        static Singleton* getInstance();
};

Singleton* Singleton::instance = 0;

Singleton* Singleton::getInstance()
{
    if (instance == 0)
    {
        instance = new Singleton();
    }

    return instance;
}

Singleton::Singleton()
{}

int main()
{
    Singleton* one = Singleton::getInstance(); 
    Singleton* two = Singleton::getInstance();

    if(one == two)
    std::cout<<"Both pointers hold same object";
    else
    std::cout<<"They don't hold same object";
    
    return 0;
}

(A) Both pointers hold same object
(B) They don't hold same object
(C) Compilation Error
(D) Exception occured

Compiler
Practitioner singleton[Posted by: Admin | Chicago, USA]

Question: 2

Note: Mandatory steps to follow while declaring Singleton class

1. Private Constructor
2. Private Copy Constructor : Not Implemented
3. Private Assignment Operator: Not Implemented

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Interview Questions on Singletone Classes in C++ : 2

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