#include <string.h>
#include <stdio.h>
#include <io.h>
void flush(FILE *stream);
int main(void)
{
   FILE *stream;
   char msg[] = "This is a test";
   /* create a file */
   stream = fopen("DUMMY.FIL", "w");
   /* write some data to the file */
   fwrite(msg, strlen(msg), 1, stream);
   printf("Press ENTER to flush DUMMY.FIL:");
   getchar();
   /* flush the data to DUMMY.FIL without closing it */
   flush(stream);
   printf("\nFile was flushed, Press ENTER to quit:");
   getchar();
   return 0;
}
void flush(FILE *stream)
{
     int duphandle;
     /* flush the stream's internal buffer */
     fflush(stream);
     /* make a duplicate file handle */
     duphandle = dup(fileno(stream));
     /* close the duplicate handle to flush the DOS buffer */
     close(duphandle);
}