From FlightSim
Code Sample: Determining which version of FS is running
void GetSimulatorVersion()
{
WIN32_FIND_DATA ffd; // file information struct
HANDLE sh;
char searchPath[MAX_PATH];
// no need for a directory qualifier because all DLL's run
// within the simulator's main folder since they run as
// children of the main simulator executable.
strcpy(searchPath, "fsx.exe");
sh = FindFirstFile(searchPath, &ffd);
if (sh == INVALID_HANDLE_VALUE)
{
strcpy(searchPath, "fs9.exe");
sh = FindFirstFile(searchPath, &ffd);
if (sh == INVALID_HANDLE_VALUE)
{
simVersion = -1;
}
else
simVersion = 9;
}
else
simVersion = 10;
}