###### (This is the legacy documentation for stable SDL2, the current stable version; [SDL3](https://wiki.libsdl.org/SDL3/) is the current development version.)
# SDL_AtomicCAS

Set an atomic variable to a new value if it is currently an old value.

## Header File

Defined in [SDL_atomic.h](https://github.com/libsdl-org/SDL/blob/SDL2/include/SDL_atomic.h)

## Syntax

```c
SDL_bool SDL_AtomicCAS(SDL_atomic_t *a, int oldval, int newval);

```

## Function Parameters

|                |                                                                      |
| -------------- | -------------------------------------------------------------------- |
| **a**          | a pointer to an [SDL_atomic_t](SDL_atomic_t) variable to be modified |
| **oldval**     | the old value                                                        |
| **newval**     | the new value                                                        |

## Return Value

Returns [SDL_TRUE](SDL_TRUE) if the atomic variable was set,
[SDL_FALSE](SDL_FALSE) otherwise.

## Remarks

***Note: If you don't know what this function is for, you shouldn't use
it!***

## Version

This function is available since SDL 2.0.0.

## See Also

* [SDL_AtomicCASPtr](SDL_AtomicCASPtr)
* [SDL_AtomicGet](SDL_AtomicGet)
* [SDL_AtomicSet](SDL_AtomicSet)

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[CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction)