Mixing Different APIs

In principle, it is no problem to use functions from different API groups within the same program simultaneously or even to access a single file. However, great care must be taken not to mix the various methods to reference a file. For example, the ANSI C FILE stream functions use a pointer to a FILE structure to reference files, while RTFiles-32 uses integer handles.

Since all possible APIs are built upon one another, a higher level API must always remember the file reference of the API it builds on. The following table shows how to translate a file reference of one API to a file reference of the next lower API level.

Destination	Source	Operations
file descriptor	class filebuf	filebuf.fd()
file descriptor	struct FILE *	fileno(FILE *)
Win32 Handle	file descriptor	_get_osfhandle(file descriptor)
RTFiles-32 Handle	Win32 Handle	RTParseHandle(Win32Handle, &Type, &RTFHandle);

Demo program FAPIDemo uses several different APIs to access a single file. It demonstrates how to translate file references between different APIs.

Left RTFiles-32 APIs

C++ iostream