C++ constructor, destructor aptitude questions and answers (set 3)

1) A constructor is called when an object is being created?

1. True
2. False

2) If you created a parameterized and a copy constructor in the class and you create an object with no arguments (0 arguments), what will be the output?

1. Program will execute successfully
2. A compile-time will occur
3. A run-time error will occur
4. A syntax error will occur

3) When a destructor is called?

1. When an object is being created
2. After destroying the object
3. We need to call destructor explicitly
4. Just before destroying an object

4) What will be the output of the following code?

#include <iostream>
using namespace std;

//class definition
class Example {
public:
    void ~Example()
    {
        cout << "Destroying the object";
    }
};

//main() code
int main()
{
    Example Ex;
    return 0;
}

1. Run-time error
2. Compile-time error
3. Destroying the object
4. Executes successfully but no output

main.cpp:7:23: error: return type specification for destructor invalid
         void ~Example()
                       ^

5) What will be the output of the following code?

#include <iostream>
using namespace std;

//class definition
class Example {
private:
    int a;
    int b;

public:
    Example(int a, int b)
    {
        this->a = a;
        this->b = b;
    }
    int get_a()
    {
        return a;
    }
    int get_b()
    {
        return b;
    }
};

//main() code
int main()
{
    Example Ex(10, 20);
    cout << "a = " << Ex.get_a() << ", b = " << Ex.get_b();

    return 0;
}

1. Compile time error
2. Run time error
3. a = 10, b = 10
4. a = 10, b = 20