VoidPointer.txt

A pointer to void is a general purpose pointer used to hold reference to hold
any data type.

void *pv;

It has two interesting properties:
1> A pointer to void will have the same representation and memory alignment 
as a pointer to char
2> A pointer to void will never be equal to another pointer.However, two void 
pointers assigned NULL values will be equal.

If a pointer is declared as global or static, it is initalized to NULL when the program starts.

malloc function is defined as 
void* malloc(size_t)

Calloc Function

void *calloc(size_t numElements, size_t elementSize);

The calloc function will allocate and clear memory at the same time.
To clear memory means it contents are set to all binary zeros.

we can also use memset that is in string.h header it require 3 arguments
pointer,value to fill, number of bytes to fill.

realloc function
defined as void *realloc(void *ptr,size_t size);

The realloc function will reallocate memory.
The function realloc returns a pointer to a block of memory.
The function takes two arguments. The first is a pointer to the original block,
and the second is the requested size.
The reallocated memory block's size will be different from the size of the 
block referenced by the first argument. The return value is a pointer to the 
reallocated memory memory.

Deallocating memory using the free function

void free(void *ptr);

The pointer argument should contain the address of memory allocated by a 
malloc type function. This is returned to the heap.

**********************************************************
If the free function is passed a null pointer, then it is
normally does nothing. If the pointer passed has been 
allocated by other than a malloc type function, then the 
function behaviour is undefined.

eg: 

int num;
int *pi = #

free(pi)        //Undefined Behaviour....
**********************************************************

when two pointer references to the same location, it is refered to as 
Aliasing.


Function Pointer Variable

void (*foo)();
*foo is function pointer variable taking void and returning void...