C++ OOPS Interview Questions

Which is the correct way to declare a class in C++?

What will this program print?

#include <iostream>
using namespace std;

class Test {
public:
    Test() { cout << "Constructor called"; }
};

int main() {
    Test obj;
    return 0;
}

Which access specifier allows members to be accessed only inside the class?

What will be the output of this program?

#include <iostream>
using namespace std;

class Person {
private:
    int age;
public:
    void setAge(int a) { age = a; }
    int getAge() { return age; }
};

int main() {
    Person p;
    p.setAge(21);
    cout << p.getAge();
    return 0;
}

Which symbol is used to denote inheritance in C++?

What will this program print?

#include <iostream>
using namespace std;

class Math {
public:
    int add(int a, int b) { return a + b; }
    double add(double a, double b) { return a + b; }
};

int main() {
    Math m;
    cout << m.add(2, 3) << " " << m.add(2.5, 3.5);
    return 0;
}

Why do we use virtual functions in C++?

What will be the output of this program?

#include <iostream>
using namespace std;

class Base {
public:
    virtual void show() { cout << "Base"; }
};

class Derived : public Base {
public:
    void show() { cout << "Derived"; }
};

int main() {
    Base *b;
    Derived d;
    b = &d;
    b->show();
    return 0;
}

What does the this pointer in C++ represent?

What will the program print?

#include <iostream>
using namespace std;

class Sample {
public:
    Sample() { cout << "Constructor "; }
    ~Sample() { cout << "Destructor"; }
};

int main() {
    Sample s;
    return 0;
}