Pointers

Pointers to objects

The objects for a class can be accessed using pointers. General form for declaring object using pointer is:

Class classname

{

member variable declaration

member function declaration and definition

}

};

classname object1;

classname *ptr;

ptr = &object1;

where

ptr – pointer variable which points the object1 in memory.

& - address operator.

*ptr – alias of object name.

Accessing member function:

General form:

Ptr → member function.

Where,

Ptr - already defined operator.

→ - class member access operator.

Member function – already declared and defined member function.

Memory allocation:

New operator is used to allocate memory space for defined object.

Syntax:

Classname *ptr = new classname

Where,

Classname – already defined and declared class.

New – keyword.

Ptr – pointer variable.

Memory deallocation:

Delete operator is used to deallocate the allocated memory space for an object.

Syntax:

Delete objectname

Where delete – keyword.

this pointer:

this is an implicit pointer to every member function in a class. This pointer gives the address of the object. Using this pointer we can access the member data in the object. General forms are:

To get the address of object

This;

To access member data

This -> name of member data;

Returning values using this pointer:

Using this pointer we can return values from member functions and over loaded operators. General form:

return * this

Pointers to derived class:

The pointers which points the derived class object is called pointers to derived class.

There are two ways of declaring derived class using pointers. They are

1) Using base class pointer. General form is

Base_class *ptr1;

Derived class D1;

Ptr1 = &D1;

2) Using derived class, general form:

derived_class *ptr2;

derived_class D2;

ptr2 = &D2

Accessing:

There are two easy of accessing derived class members using pointer.

They are

1)Using base class pointer. General form is

((derived_class*) base_pointer) -> member

2)Using derived class pointer. General form is

Derived_class_pointer ->member