_filelength, _filelengthi64

Visual Studio 6.0

Get the length of a file.

long _filelength( int handle );

__int64 _filelengthi64( int handle );

Function Required Header Compatibility
_filelength <io.h> Win 95, Win NT
_filelengthi64 <io.h> Win 95, Win NT

For additional compatibility information, see Compatibility in the Introduction.


LIBC.LIB Single thread static library, retail version
LIBCMT.LIB Multithread static library, retail version
MSVCRT.LIB Import library for MSVCRT.DLL, retail version

Return Value

Both _filelength and _filelengthi64 return the file length, in bytes, of the target file associated with handle. Both functions return a value of –1L to indicate an error, and an invalid handle sets errno to EBADF.



Target file handle


/* CHSIZE.C: This program uses _filelength to report the size
 * of a file before and after modifying it with _chsize.

#include <io.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>

void main( void )
   int fh, result;
   unsigned int nbytes = BUFSIZ;

   /* Open a file */
   if( (fh = _open( "data", _O_RDWR | _O_CREAT, _S_IREAD
                   | _S_IWRITE ))  != -1 )
      printf( "File length before: %ld\n", _filelength( fh ) );
      if( ( result = _chsize( fh, 329678 ) ) == 0 )
         printf( "Size successfully changed\n" );
         printf( "Problem in changing the size\n" );
      printf( "File length after:  %ld\n", _filelength( fh ) );
      _close( fh );


File length before: 0
Size successfully changed
File length after:  329678

File Handling Routines

See Also   _chsize, _fileno, _fstat, _fstati64, _stat, _stati64