ERR - QB64Official/qb64 GitHub Wiki
The ERR function returns the last QBasic error code number.
Syntax
errorNum% = ERR
Description
- If there is no error, the function returns 0
 - Can be used in an error handling routine to report the last error code number.
 
Example(s)
Simulating an error to test a program error handler that looks for a "Subscript out of range" error.
ON ERROR GOTO handler
IF x = 0 THEN ERROR 111  'simulate an error code that does not exist
x = x + 1
IF x THEN ERROR 9        'simulate array boundary being exceeded
END
handler:
PRINT ERR, _ERRORLINE
BEEP
IF ERR = 9 THEN
  PRINT "The program has encountered an error and needs to close! Press a key!"
  K$ = INPUT$(1)
  SYSTEM
END IF
RESUME NEXT               'RESUME can only be used in error handlers