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To check for a null pointer, you can use an ‘if’ statement as follows:

if(ptr) /* succeeds if p is not null */
if(!ptr) /* succeeds if p is null */

Pointers in Detail
Pointers have many but easy concepts and they are very important to C programming. The
following important pointer concepts should be clear to any C programmer:

Concept Description

Pointer arithmetic There are four arithmetic operators that can
be used in pointers: ++, --, +, -

Array of pointers You can define arrays to hold a number of
pointers.

Pointer to pointer C allows you to have pointer on a pointer
and so on.

Passing pointers to functions in C Passing an argument by reference or by
address enable the passed argument to be changed
in the calling function by the called function.

Return pointer from functions in C allows a function to return a pointer to
C the local variable, static variable, and dynamically
allocated memory as well.

Pointer Arithmetic
A pointer in C is an address, which is a numeric value. Therefore, you can perform
arithmetic operations on a pointer just as you can on a numeric value. There are four arithmetic
operators that can be used on pointers: ++, --, +, and
-
To understand pointer arithmetic, let us consider that ptr is an integer pointer which
points to the address 1000. Assuming 32-bit integers, let us perform the following arithmetic
operation on the pointer:

10
4