fileno()                Get File Handle Associated with Stream (Macro)

 #include   <stdio.h>

 int        fileno(stream);
 FILE       *stream;                     Pointer to file structure

    fileno() returns the handle associated with 'stream'.  If more than
    one handle is associated with 'stream', fileno() returns the handle
    assigned when the stream was opened.

       Returns:     The file handle.  There is no error return.  If the
                    stream does not specify an open file, the result is
                    undefined.

   Portability:     Not supported by ANSI standard.

   -------------------------------- Example ---------------------------------

    The following statements open a file and check its length.

           #include <stdio.h>
           #include <io.h>

           FILE *stream;
           long length;

           main()
           {
               if ((stream = fopen("work.dat","r+"))!= NULL) {
                  length = filelength(fileno(stream));
               }
           }