Question

I just need some clarification on variables

A normal variable has 2 “parts” to it?
one part is the actual value and the other part is the location of that value in the memory

Is that right?

So a pointer variable is just the location part of a normal variable, and it doesn’t have value itself?

Answer 1

If you’re talking about C, then pointers simply represent another level of indirection.

If you consider the variable a as an integer, &a (address of a) is the location and it contains the value of a in that location. When you use a, you will get the value from the address.

A pointer variable p, when used, will also get a value from a location. But the value at that location is another location from which you can get a value.

So let’s say you have:

int a = 7;     // set a to 7.
int *p = &a;   // set p to the address of a.

In this example, a is the variable on the stack at location 0x1234 and p is on the stack at location 0x1236 (a 16-bit int/pointer system). What you have in memory is:

           +--------+
0x1236 (p) | 0x1234 |
           +--------+
0x1234 (a) | 0x0007 |
           +--------+

When you use a with, for example:

int b = a;

the value of a at memory location 0x1234 is used to set b. However, with a pointer:

int c = *p;

you first look up the value of p in memory location 0x1236 (the value is 0x1234), then dereference it (with ‘*’) to get the value of a.