_tell, _telli64

Get the position of the file pointer.

Syntax

long _tell(
   int handle
);
__int64 _telli64(
   int handle
);

Parameters

handle
File descriptor referring to open file.

Return value

The current position of the file pointer. On devices incapable of seeking, the return value is undefined.

A return value of -1L indicates an error. If handle is an invalid file descriptor, the invalid parameter handler is invoked, as described in Parameter validation. If execution is allowed to continue, these functions set errno to EBADF and return -1L.

For more information about return codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

Remarks

The _tell function gets the current position of the file pointer (if any) associated with the handle argument. The position is expressed as the number of bytes from the beginning of the file. For the _telli64 function, this value is expressed as a 64-bit integer.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

For more compatibility information, see Compatibility.

Example

// crt_tell.c
// This program uses _tell to tell the
// file pointer position after a file read.
//

#include <io.h>
#include <stdio.h>
#include <fcntl.h>
#include <share.h>
#include <string.h>

int main( void )
{
   int  fh;
   char buffer[500];

   if ( _sopen_s( &fh, "crt_tell.txt", _O_RDONLY, _SH_DENYNO, 0) )
   {
      char buff[50];
      _strerror_s( buff, sizeof(buff), NULL );
      printf( buff );
      exit( -1 );
   }

   if( _read( fh, buffer, 500 ) > 0 )
      printf( "Current file position is: %d\n", _tell( fh ) );
   _close( fh );
}

Input: crt_tell.txt

Line one.
Line two.

Output

Current file position is: 20

See also

Low-level I/O
ftell, _ftelli64
_lseek, _lseeki64