Closes a file.
The _close function closes the file associated with fd.
The file descriptor and the underlying OS file handle are closed. Thus, it is not necessary to call CloseHandle if the file was originally opened using the Win32 function CreateFile and converted to a file descriptor using _open_osfhandle.
This function validates its parameters. If fd is a bad file descriptor, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, the functions returns -1 and errno is set to EBADF.
For more compatibility information, see Compatibility in the Introduction.