Changes the file size.
int _chsize( int handle, long size );
| 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