###### (This is the documentation for SDL3, which is the current stable version. [SDL2](https://wiki.libsdl.org/SDL2/) was the previous version!) # SDL_Swap64 Byte-swap an unsigned 64-bit number. ## Header File Defined in [](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_endian.h) ## Syntax ```c SDL_FORCE_INLINE Uint32 SDL_Swap64(Uint64 x); ``` ## Function Parameters | | | | | ---------------- | ----- | ----------------------- | | [Uint64](Uint64) | **x** | the value to byte-swap. | ## Return Value ([Uint32](Uint32)) Returns `x`, with its bytes in the opposite endian order. ## Remarks This will always byte-swap the value, whether it's currently in the native byteorder of the system or not. You should use [SDL_Swap64LE](SDL_Swap64LE) or [SDL_Swap64BE](SDL_Swap64BE) instead, in most cases. Note that this is a forced-inline function in a header, and not a public API function available in the SDL library (which is to say, the code is embedded in the calling program and the linker and dynamic loader will not be able to find this function inside SDL itself). ## Thread Safety It is safe to call this function from any thread. ## Version This function is available since SDL 3.1.3. ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryEndian](CategoryEndian)