What is the difference between a pointer and a reference?

Answer 1

To make it simple there is no difference between them as far as i or u see the internal picture. It is just how compilers implements the two different statements int *x=&y and int &x=y.
But Now coming to concepts. There are whole bunch of difference between them. A pointer is a variable which holds the address of some other variable while a reference is an alias to some variable.

To get deeper understanding u can read article.
http://www.embedded.com/electronics-blogs/programming-pointers/4023307/References-vs-Pointers

Comments

Well explained Prakash, let me put my view point -

A pointer is a variable which holds the address of some other variable while a reference is an alias to some variable. On the implementation front it is implemented as const pointer which is implicitly dereferenced.

Answer 2

Reference:

A reference must always refer to some object and, therefore, must always be initialized;

Pointer:

pointers do not have such restrictions. A pointer can be reassigned to point to different objects while a reference always refers to an object with which it was initialized.

Answer 3

OK, that covers the difference(s) between pointers and references. Now, why was reference created at all? What was the need when pointer was already there?

Mr. Bjarne Stroustrup introduced references in C++ to support operator overloading. Consider the following code fragment for subtracting 2 objects and storing it in 3rd:

a = &b - &c;

where a, b and c are the objects with an overloaded '-' operator. Isn't the syntax 'un-natural'? To make it more natural he have introduced references. With references in place, the above line becomes:

a = b - c;

Simple, isn't it? :)

Another thing that comes to my mind apart from this is, how ugly the copy constructors would have been without the presence of references.

Another reason I love C++ !!