realloc - memory reallocator

Syntax	#include <stdlib.h> void *realloc(void *ptr, size_t size);
Description	realloc() changes the size of the memory area pointed to by ptr to size bytes. realloc() is part of a C-specific memory management package that internally administers memory areas which are requested and subsequently freed. As far as possible, all new requests are first satisfied from the areas that are already being managed, and only then from the operating system. ptr is a pointer to the start of the memory area to be altered. It must be a pointer that was returned earlier by malloc() or calloc(). size is an integer value that specifies the new size in bytes.
Return val.	Pointer to the start of the reallocated memory area
		if successful.
	Null pointer	if realloc() could not reallocate the space, e.g. because there was not enough memory available or because an error occurred. errno is set to indicate the error.
Errors	realloc() will fail if: ENOMEM      There is not enough memory available.
Notes	Changing the size of a memory area with realloc() may cause the allocated block to be shifted. In such cases, the contents of the pointer passed as an argument are not identical to the return value. The contents of the block are preserved up to the minimum of the old (when enlarging) and new (when reducing) sizes. If realloc() returns a null pointer, the block to which ptr points may have been destroyed! If ptr is a null pointer, realloc() has the same effect as a malloc call for the specified size.
See also	calloc(), free(), malloc(), stdlib.h.