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fileno

Usage

   #include <stdio.h>
   int fileno(FILE *fp);

Description

   fileno returns the file descriptor associated with stream fp. The fp
   argument must point to a file which is already open.

   The fileno function converts a file pointer to a file descriptor for use
   with the low-level file functions such as close, read and write. Mixing
   of high and low level functions is not recommended.

Example 

   #include <stdio.h>
   #include <stdlib.h>

   int main()
   {

       int fd;
       fd = fileno(stderr);
       printf("The file handle for stderr is %d\n",fd);
       fd = fileno(stdaux);
       printf("The file handle for stdaux is %d\n",fd);
       fd = fileno(stdprn);
       printf("The file handle for stdprn is %d\n",fd);
       return EXIT_SUCCESS;
   }

Return Value

   fileno returns the file descriptor. There is no error return.

See Also

   fopen, freopen