Null Pointer

What is Null Pointer?

With reference to the computer memory, the term ‘null pointer’ signifies a specific type of command that is used to direct the operating system or the software to a vacant location in it.

Technically, a null pointer means the command that essentially indicates the end of a processing task or a memory search event.

However, with reference to programming, it denotes a pointer that does not point to any function or object.

Understanding Null Pointer

Understanding Null Pointer

A null pointer is a special reserved value. It is usually demarcated in the stddef header file.

It does not point to any specific location. To be more precise, the null pointer refers to the 0th location in the memory of a computer.

However, the pointer typically directs the software or the operating system to an empty space on the memory.

In simple terms, when an address is not assigned to a pointer, then it is usually referred to as a null pointer. However, it is usually done by assigning a 0 or a NULL value to the pointer.

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A null pointer is typically used in the following situations:

Null pointer constants

In order to ensure that the pointer does not point towards any valid function or an object stored in the memory of the computer, a null pointer constant is used.

A null pointer constant typically refers to a specific type of integer constant expression which estimates to zero.

This means that a null pointer constant may eventually evaluate to 0, 0L or any other specific type of expression that may be cast to 0 (void *).

There are typically two such null pointer constant expressions used to specify the values, such as:


A few examples of null pointers are:


The set of rules to follow for creating a null pointer are as follows:

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This ends the process.

Null Pointer Vs Void Pointer

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So now you know that a null pointer points to nothing. However, this is not the same as the uninitialized pointer and therefore should not be confused with it.

A null pointer will never point to any valid object or function but an uninitialized pointer may, and therefore it can be both valid and null pointer at different times.