a UTF-8 string representing the filename to open.
an ASCII string representing the mode to be used for opening the file.
a pointer to the SDL_AsyncIO structure that is created or NULL on failure; call SDL_GetError for more information.
Available since SDL 3.2.0.
Use this function to create a new SDL_AsyncIO object for reading from and/or writing to a named file.
The mode string understands the following values: - "r": Open a file for reading only. It must exist. - "w": Open a file for writing only. It will create missing files or truncate existing ones. - "r+": Open a file for update both reading and writing. The file must exist. - "w+": Create an empty file for both reading and writing. If a file with the same name already exists its content is erased and the file is treated as a new empty file.
There is no "b" mode, as there is only "binary" style I/O, and no "a" mode for appending, since you specify the position when starting a task. This function supports Unicode filenames, but they must be encoded in UTF-8 format, regardless of the underlying operating system.
This call is _not_ asynchronous; it will open the file before returning, under the assumption that doing so is generally a fast operation. Future reads and writes to the opened file will be async, however.