tell-telli64.md

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Learn more about: _tell, _telli64	_tell, _telli64	4/2/2020	_telli64 _tell _o__tell _o__telli64	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-stdio-l1-1-0.dll	DLLExport	apiref	CORECRT_IO/_tell CORECRT_IO/_telli64 _tell _telli64	tell function file pointers [C++], getting _tell function file pointers [C++] telli64 function _telli64 function	1500e8f9-8fec-4253-9eec-ec66125dfc9b

_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

Routine	Required header
_tell, _telli64	<io.h>

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