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NULL Macro is simply what is defined as 0 in a macro provided by the library

Null pointer is a pointer which has 0 or NULL value stored and points to nowhwere still it points to 0x00 i.e. the first memory location of the OS

Null pointer != Uninitialized pointer because an uninitialised pointer can point anywhere in the memory location ...but a NULL pointer surely points to no where(but still behind the scene we can say that it only points to 0x00). Never we can retrive a Null pointer location using th"&" operator..neither will malloc/calloc return NULL IF THERE IS SPACE IN THE MEMORY. NULL pointer is unique !!

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โˆ™ 2008-02-24 14:20:33
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Q: What is a null macro what is the difference between a null pointer and a null macro?
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What is the difference between a null pointer and a null macro?

A null pointer is a pointer variable with the value 0. A null macro is a macro that defines the NULL symbol (typically 0L on a 32-bit system).


What is the difference between void pointer 0 and NULL.?

If by 'void pointer 0' you mean '(void *)0', then it is equal to NULL.


What is the difference between void pointers and null pointers?

A void pointer is a pointer that has no type information attached to it.A null pointer is a pointer that points to "nothing". A null pointer can be of any type (void included, of course).


What is Difference between null macro and null pointer?

Using a NULL macro to make C portableI'll assume that you're asking your question for C type language programming. A NULL pointer is a pointer that's guarnteed to point to nothing. This may be 0 in a UNIX/Linux system or some other address in another system. Using the NULL macro to set/initialize your pointers will make your programs more portable among systems than using something like the 0.#include char *c = 0; // initialize to NULL--not portablechar *p = NULL; // initialize to NULL as defined in stdio is portableAddendumThe code:char *c = 0;actually is portable because the compiler converts 0's used in a pointer context (cast to a pointer) to the machine's representation of a NULL pointer, which may or may not be all 0 bits. The NULL macro itself might be defined as something like 0 or (void *)0, and both definitions are portable. As a corollary, the following code is also portable:if (!c) {// do something}because it is equivalent to:if (c != 0) {// do something}and the 0 above is converted to a NULL pointer because it is being compared with a pointer.


What is NULL Pointer?

There are times when it is necessary to have a pointer that doesn't point to anything. The macro NULL, defined in , has a value that's guaranteed to be different from any valid pointer. NULL is a literal zero, possibly cast to void* or char*.


Difference between void pointer and null pointer?

A Null pointer has the value 0. void pointer is a generic pointer introduced by ANSI. Before ANSI, char pointers are used as generic pointer. Generic pointer can hold the address of any data type. Pointers point to a memory address, and data can be stored at that address.


What is null macro?

The NULL macro is an implementation-defined macro. It is used to symbolise the zero address (0x0) in C programs and older C++ programs. It is not type safe, but is the conventional method of assigning the zero address to a pointer variable. C++11 introduced the type-safe nullptr data type.


What is null pointer error?

For example, if you write NULl instead of NULL.


What is a NULL Macro?

# define pi 3.17 // tihs is a preprocessing directive macro. "pi" is called macro template " 3.17" is the macro value. means in entire program pi value is 3.17. if we declared like # define pi 0 means pi value is zero means null. so the macro template which carries a null value is called a NULL MACRO.


What is the use of null pointer?

Pointer is a variable that stores address of a variable . A NULL Pointer a pointer that doesn't point to anything, it is a literal zero .Some people ,notably C++ programmers, prefer to use 0 rather than NULL.


When you let your pointer linger over an object the pointer is?

The pointer is non-NULL.


What is null pointer and is it same as an uninitialized pointer?

An uninitialized pointer is a pointer that has not been assigned a value; it's uninitialized.The value of an uninitialized pointer is undefined (it could be anything).A null pointer is simply a pointer that has a value of NULL.A word of advice: initialize your pointers to NULL.This allows you to see that the pointer is invalid; to check if an uninitialized pointer is valid is quite impossible.Examples:Uninitialized:int *myPointer;Null-pointer:int *myNullPointer = NULL;Dereferencing either of these pointers is something you'll like to avoid.It is very common in a program to check for null pointers; some functions return NULL on failure, for example:struct Foo *result = doSomething();if (result == NULL) {printf("Error: The function doSomething() returned NULL);return;} else {printf("The result: %d", result->bar);}

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