fsetpos

Sets the stream-position indicator.

int fsetpos( FILE *stream, const fpos_t *pos );

For additional compatibility information, see Compatibility in the Introduction.

Libraries

Return Value

If successful, fsetpos returns 0. On failure, the function returns a nonzero value and sets errno to one of the following manifest constants (defined in ERRNO.H): EBADF, which means the file is not accessible or the object that stream points to is not a valid file handle; or EINVAL, which means an invalid stream value was passed.

Parameters

stream

Pointer to FILE structure

pos

Position-indicator storage

Remarks

The fsetpos function sets the file-position indicator for stream to the value of pos, which is obtained in a prior call to fgetpos against stream. The function clears the end-of-file indicator and undoes any effects of ungetc on stream. After calling fsetpos, the next operation on stream may be either input or output.

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   fgetpos