_chsize

Changes the file size.

int_chsize(inthandle**,longsize);**

Routine Required Header Optional Headers Compatibility
_chsize <io.h> <errno.h> Win 95, Win NT

For additional compatibility information, see Compatibility in the Introduction.

Libraries

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

_chsize returns the value 0 if the file size is successfully changed. A return value of –1 indicates an error: errno is set to EACCES if the specified file is locked against access, to EBADF if the specified file is read-only or the handle is invalid, or to ENOSPC if no space is left on the device.

Parameters

handle

Handle referring to open file

size

New length of file in bytes

Remarks

The _chsize function extends or truncates the file associated with handle to the length specified by size. The file must be open in a mode that permits writing. Null characters ('\0') are appended if the file is extended. If the file is truncated, all data from the end of the shortened file to the original length of the file is lost.

Example

/* 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" );
      else
         printf( "Problem in changing the size\n" );
      printf( "File length after:  %ld\n", _filelength( fh ) );
      _close( fh );
   }
}

Output

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

File Handling Routines

See Also   _close, _creat, _open