View source for DosUnsetExceptionHandler

Removes an exception handler from a thread's chain of exception handlers.

==Syntax==
 DosUnsetExceptionHandler(pERegRec)

==Parameters==
;pERegRec (PEXCEPTIONREGISTRATIONRECORD) - input : A pointer to the exception registration record that describes the exception handler to be unregistered.

==Return Code==
;ulrc (APIRET) - returns:DosUnsetExceptionHandler returns one of the following values:
* 0  NO_ERROR
* 87 ERROR_INVALID_PARAMETER

==Remarks==
Note: Do not make Presentation Manager calls from exception handlers.

DosUnsetExceptionHandler deregisters (removes) an exception handler from a thread's chain of registered exception handlers.

For a detailed list of the system exceptions, see System Exceptions. 

==Example Code==
This example sets and unsets an exception handler named "MyTermhandler" from the thread's chain of exception handlers.
<PRE>
#define INCL_DOSPROCESS       /* DOS process values (for DosSleep) */
#define INCL_DOSEXCEPTIONS    /* DOS exception values */
#define INCL_ERRORS           /* DOS error values     */
#include <os2.h>
#include <stdio.h>

ULONG _System MyTermHandler( PEXCEPTIONREPORTRECORD       p1,
                             PEXCEPTIONREGISTRATIONRECORD p2,
                             PCONTEXTRECORD               p3,
                             PVOID                        pv );

int main (VOID)
{
  EXCEPTIONREGISTRATIONRECORD RegRec  = {0};  /* Exception Registration Record */
  APIRET      rc      = NO_ERROR;   /* Return code                   */

  /* Add MyTermHandler to this thread's chain of exception handlers */

  RegRec.ExceptionHandler = (ERR)MyTermHandler;
  rc = DosSetExceptionHandler( &RegRec );
  if (rc != NO_ERROR) {
     printf("DosSetExceptionHandler error: return code = %u\n",rc);
     return 1;
  }

  printf("Terminate this program using Ctrl-C or Ctrl-Break.\n");

  rc = DosSleep(60000L);   /* Give user plenty of time to comply... */

  rc = DosUnsetExceptionHandler( &RegRec );
  if (rc != NO_ERROR) {
     printf("DosUnsetExceptionHandler error: return code = %u\n",rc);
     return 1;
  }
  return NO_ERROR;
}
/***************************************************************************/
ULONG _System MyTermHandler( PEXCEPTIONREPORTRECORD       p1,
                             PEXCEPTIONREGISTRATIONRECORD p2,
                             PCONTEXTRECORD               p3,
                             PVOID                        pv )
{
  printf("*** MyTermHandler entered: ExceptionNum = %x\n",p1->ExceptionNum);

  switch( p1->ExceptionNum) {
   case XCPT_SIGNAL: {
      printf(" XCPT_SIGNAL");
      switch( p1->ExceptionInfo[0] ) {
        case XCPT_SIGNAL_INTR:     { printf("_INTR"); break; }
        case XCPT_SIGNAL_KILLPROC: { printf("_KILLPROC"); break; }
        case XCPT_SIGNAL_BREAK:    { printf("_BREAK"); break; }
        default:;
      }
      printf("\n"); break;
   }
   case XCPT_PROCESS_TERMINATE:       { printf(" Process Terminate \n"); break;}
   case XCPT_ASYNC_PROCESS_TERMINATE: { printf(" Async Process Term\n"); break;}
   case XCPT_UNWIND:                  { printf(" XCPT_UNWIND\n");        break;}
   default:;
  }

  return XCPT_CONTINUE_SEARCH;          /* Exception not resolved... */
}
</PRE>

==Related Functions==
* [[DosAcknowledgeSignalException]]
* [[DosEnterMustComplete]]
* [[DosExitMustComplete]]
* [[DosRaiseException]]
* [[DosSendSignalException]]
* [[DosSetExceptionHandler]]
* [[DosSetSignalExceptionFocus]]
* [[DosUnwindException]]

[[Category:Dos]]