auromita

• Jul 22nd, 2006

 

Null macro is defined in stdio.h and stddef.h.It is used to represent a null pointer in your code.

its value is zero.

Null pointer is same as an uninitialized pointer..It does not point anywhere.

shaanxxx

• Aug 20th, 2006

 

NULL MACRO = (void *) 0Null pointer contains zeroth location chat *ptr = 0;you can use zero instead of NULL macro (I AM TALING ABOUT C). It will harm you.

tirthankar

• Feb 27th, 2007

 

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 !!

dasam

 Profile Answers by dasam 

• Mar 31st, 2007

 

NULL MACRO : #define NULL 0NULL Pointer : int* ptr = NULL; //points to no whereuninitialised pointer : int* ptr; //points to anywhere

vivianyang

 Profile Answers by vivianyang 

• May 11th, 2008

 

A null pointer should not be confused with an uninitialized pointer: a null pointer is guaranteed to compare unequal to any valid pointer, whereas depending on the language and implementation an uninitialized pointer might have either an indeterminate (random or meaningless) value or might be initialised to an initial constant (possibly but not necessarily NULL).

In C and C++ programming, two null pointers are guaranteed to compare equal; ANSI C guarantees that any NULL pointer will be equal to 0 in a comparison with an integer type.