###### (This is the legacy documentation for SDL2, the previous stable version; [SDL3](https://wiki.libsdl.org/SDL3/) is the current stable version.)
# SDL_Direct3D9GetAdapterIndex

Get the D3D9 adapter index that matches the specified display index.

## Header File

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

## Syntax

```c
int SDL_Direct3D9GetAdapterIndex( int displayIndex );
```

## Function Parameters

|     |                  |                                                            |
| --- | ---------------- | ---------------------------------------------------------- |
| int | **displayIndex** | the display index for which to get the D3D9 adapter index. |

## Return Value

(int) Returns the D3D9 adapter index on success or a negative error code on
failure; call [SDL_GetError](SDL_GetError)() for more information.

## Remarks

The returned adapter index can be passed to `IDirect3D9::CreateDevice` and
controls on which monitor a full screen application will appear.

## Version

This function is available since SDL 2.0.1.

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