Gets register values returned by 0x59.
#include <dos.h>
int _dosexterr( struct _DOSERROR *errorinfo );
| errorinfo | Extended DOS error information |
The _dosexterr function obtains the extended error information returned by DOS system call 0x59 and stores the values in the structure pointed to by errorinfo. This function is useful when making system calls with DOS versions 3.0 or later, which offer extended error handling.
The structure type _DOSERROR is defined in DOS.H. The _DOSERROR structure contains the following elements:
| Element | Description |
| int exterror | AX register contents |
| char errclass | BH register contents |
| char action | BL register contents |
| char locus | CH register contents |
Giving a NULL pointer argument causes _dosexterr to return the value in AX without filling in the structure fields. See MS-DOS Encyclopedia (Duncan, ed.; Redmond, WA: Microsoft Press, 1988) or Programmer's PC Sourcebook 2nd ed. (Hogan; Redmond, WA: Microsoft Press, 1991) for more information on the register contents.
The _dosexterr function returns the value in the AX register (identical to the value in the exterror structure field).
Standards:None
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:None
The _dosexterr function should be used only with DOS versions 3.0 or later.
/* DOSEXERR.C: This program tries to open the file test.dat.
* If the attempted open operation fails, the program uses
* _dosexterr to display extended error information.
*/
#include <dos.h>
#include <io.h>
#include <fcntl.h>
#include <stdio.h>
void main( void )
{
struct _DOSERROR doserror;
int fd;
/* Attempt to open a non-existent file */
if( (fd = _open( "NOSUCHF.ILE", _O_RDONLY )) == -1 )
{
_dosexterr( &doserror );
printf( "Error: %d Errclass: %d Action: %d Locus: %d\n",
doserror.exterror, doserror.errclass,
doserror.action, doserror.locus );
}
else
{
printf( "Open succeeded so no extended information printed\n" );
_close( fd );
}
}
Error: 2 Errclass: 8 Action: 3 Locus: 2