Object Oriented Programming : Practice Questions and Answers

Although the object constructor is called only ones, the destructor will be called twice, because of destroying the copy of the object that is temporarily created. This is the concept of how the object should be passed and manipulated.

Like any other value, only one object can be returned at ones. The only possible way to return more than one object is to return address of an object array. But that again comes under returning object pointer.

The problem can be solved by overloading the assignment operator to get the values that might be getting returned while the destructor free the dynamic memory. Defining copy constructor can help us to do this in even simpler way.

The destruction of temporary variable may give rise to unexpected logical errors. Consider the destructor which may free the dynamically allocated memory. But this may abort the program if another is still trying to copy the values from that dynamic memory.

The temporary object is created. It holds the return value. The values gets assigned as required, and the temporary object gets destroyed.

Even though the constructor is not called when the object is passed to a function, the copy of the object is still created, where the values of the members are same. When the object have to be destroyed, the destructor is called to free the memory and resources that the object might have reserved.

When an object is passed by reference, its address is passed implicitly. This will make changes to the main function whenever any modification is done.

Pass by address uses the explicit address passing to the function whereas pass by reference implicitly passes the address of the object.

When an object is passed by value, a new object is created implicitly. This new object uses the implicit values assignment, same as that of the object being passed.

The objects can be passed in three ways. Pass by value, pass by reference and pass by address. These are the general ways to pass the objects to a function.

The copy constructors are always overloaded constructors. They have to be. All the classes have a default constructor and other constructors are basically overloaded constructors.

The object should not be modified in the copy constructor. Because the object itself is being copied. When the object is returned from a function, the object must be a constant otherwise the compiler creates a temporary object which can die anytime.

The copy constructor can be defined as private. If we make it private then the objects of the class can’t be copied. It can be used when a class used dynamic memory allocation.

While using explicit copy constructor, the pointers of copied object point to the intended memory location. This is assured since the programmers themselves manipulate the addresses.

Whenever the compiler creates a temporary object, copy constructor is used to copy the values from existing object to the temporary object.

All the options given, directly or indirectly indicate that the object is being passed by reference. And if object is not passed by reference then the out of memory error is produced. Due to infinite constructor call of itself.

This is mandatory to pass the object by reference. Otherwise, the object will try to create another object to copy its values, in turn a constructor will be called, and this will keep on calling itself. This will cause the compiler to give out of memory error.

The syntax must contain the class name first, followed by the classname as type and &object within parenthesis. Then comes the constructor body. The definition can be given as per requirements.

In the case where dynamic memory allocation is used, the copy constructor definition must be given. The implicit copy constructor is not capable of manipulating the dynamic memory and pointers. Explicit definition allows to manipulate the data as required.

The compiler provides an implicit copy constructor. It is not mandatory to always create an explicit copy constructor. The values are copied using implicit constructor only.