fgetpos

Gets a stream’s file-position indicator.

intfgetpos(FILE*stream,fpos_t*pos);

For additional compatibility information, see Compatibility in the Introduction.

Libraries

Return Value

If successful, fgetpos returns 0. On failure, it returns a nonzero value and sets errno to one of the following manifest constants (defined in STDIO.H): EBADF, which means the specified stream is not a valid file handle or is not accessible, or EINVAL, which means the stream value is invalid.

Parameters

stream

Target stream

pos

Position-indicator storage

Remarks

The fgetpos function gets the current value of the stream argument’s file-position indicator and stores it in the object pointed to by pos. The fsetpos function can later use information stored in pos to reset the stream argument’s pointer to its position at the time fgetpos was called. The pos value is stored in an internal format and is intended for use only by fgetpos and fsetpos.

Example

/* FGETPOS.C: This program opens a file and reads
 * bytes at several different locations.
 */

#include <stdio.h>

void main( void )
{
   FILE   *stream;
   fpos_t pos;
   char   buffer[20];

   if( (stream = fopen( "fgetpos.c", "rb" )) == NULL )
      printf( "Trouble opening file\n" );
   else
   {
      /* Read some data and then check the position. */
      fread( buffer, sizeof( char ), 10, stream );
      if( fgetpos( stream, &pos ) != 0 )
         perror( "fgetpos error" );
      else
      {
         fread( buffer, sizeof( char ), 10, stream );
         printf( "10 bytes at byte %ld: %.10s\n", pos, buffer );
      }

   /* Set a new position and read more data */
   pos = 140;
   if( fsetpos( stream, &pos ) != 0 )
      perror( "fsetpos error" );

   fread( buffer, sizeof( char ), 10, stream );
   printf( "10 bytes at byte %ld: %.10s\n", pos, buffer );
   fclose( stream );
   }
}

Output

10 bytes at byte 10: .C: This p
10 bytes at byte 140:
{
   FIL

Stream I/O Routines

See Also   fsetpos