# SDL_realloc

Change the size of allocated memory.

## Header File

Defined in [<SDL3/SDL_stdinc.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_stdinc.h)

## Syntax

```c
void * SDL_realloc(void *mem, size_t size);
```

## Function Parameters

|        |          |                                                       |
| ------ | -------- | ----------------------------------------------------- |
| void * | **mem**  | a pointer to allocated memory to reallocate, or NULL. |
| size_t | **size** | the new size of the memory.                           |

## Return Value

(void *) Returns a pointer to the newly allocated memory, or NULL if
allocation failed.

## Remarks

The memory returned by this function must be freed with
[SDL_free](SDL_free)().

If `size` is 0, it will be set to 1. Note that this is unlike some other C
runtime `realloc` implementations, which may treat `realloc(mem, 0)` the
same way as `free(mem)`.

If `mem` is NULL, the behavior of this function is equivalent to
[SDL_malloc](SDL_malloc)(). Otherwise, the function can have one of three
possible outcomes:

- If it returns the same pointer as `mem`, it means that `mem` was resized
  in place without freeing.
- If it returns a different non-NULL pointer, it means that `mem` was freed
  and cannot be dereferenced anymore.
- If it returns NULL (indicating failure), then `mem` will remain valid and
  must still be freed with [SDL_free](SDL_free)().

If the allocation is successfully resized, the returned pointer is
guaranteed to be aligned to either the *fundamental alignment*
(`alignof(max_align_t)` in C11 and later) or `2 * sizeof(void *)`,
whichever is smaller.

## Thread Safety

It is safe to call this function from any thread.

## Version

This function is available since SDL 3.2.0.

## See Also

- [SDL_free](SDL_free)
- [SDL_malloc](SDL_malloc)
- [SDL_calloc](SDL_calloc)

----
[CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryStdinc](CategoryStdinc)

