|
|
Back to UserFriendly Strip Comments Index
|
Your friend, "realloc", munger of heaps. | by LionsPhil | 2004-02-10 16:05:14 |
| [dev@somebox.fi ~]$ man 3 realloc |
by wheresthefish |
2004-02-10 16:19:25 |
MALLOC(3) Linux Programmer's Manual MALLOC(3)
NAME
calloc, malloc, free, realloc - Allocate and free dynamic memory
SYNOPSIS
#include <stdlib.h>
void *calloc(size_t nmemb, size_t size);
void *malloc(size_t size);
void free(void *ptr);
void *realloc(void *ptr, size_t size);
DESCRIPTION
calloc() allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated mem
ory. The memory is set to zero.
malloc() allocates size bytes and returns a pointer to the allocated memory. The memory is not cleared.
free() frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc()
or realloc(). Otherwise, or if free(ptr) has already been called before, undefined behaviour occurs. If ptr is NULL,
no operation is performed.
realloc() changes the size of the memory block pointed to by ptr to size bytes. The contents will be unchanged to the
minimum of the old and new sizes; newly allocated memory will be uninitialized. If ptr is NULL, the call is equivalent
to malloc(size); if size is equal to zero, the call is equivalent to free(ptr). Unless ptr is NULL, it must have been
returned by an earlier call to malloc(), calloc() or realloc().
RETURN VALUE
For calloc() and malloc(), the value returned is a pointer to the allocated memory, which is suitably aligned for any
kind of variable, or NULL if the request fails.
free() returns no value.
realloc() returns a pointer to the newly allocated memory, which is suitably aligned for any kind of variable and may be
different from ptr, or NULL if the request fails. If size was equal to 0, either NULL or a pointer suitable to be passed
to free() is returned. If realloc() fails the original block is left untouched - it is not freed or moved.
That last line is the clue really. AFAICT it depends on the input pointer. You only need to free() if you've already got memory allocated.
|
|
[ Reply ] |
|
Ah, but here's the tricky bit. | by LionsPhil | 2004-02-10 16:32:46 |
|
Never mind. | by LionsPhil | 2004-02-10 16:39:59 |
|
free(NULL) can crash some systems | by Slamlander | 2004-02-10 18:20:35 |
|
|
[Todays Cartoon Discussion]
[News Index]
|
|
