Uses of NULL Pointer in C

Following are some most common uses of the NULL pointer in C:

1. To initialize a pointer variable when that pointer variable hasn’t been assigned any valid memory address yet.
2. To check for a null pointer before accessing any pointer variable. By doing so, we can perform error handling in pointer-related code, e.g., dereference a pointer variable only if it’s not NULL.
3. To pass a null pointer to a function argument when we don’t want to pass any valid memory address.
4. A NULL pointer is used in data structures like trees, linked lists, etc. to indicate the end.

The Null Pointer is the pointer that does not point to any location but NULL. According to C11 standard:

“An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant. If a null pointer constant is converted to a pointer type, the resulting pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function.”