Avoid trapping error 0

[DienyduToit]

The function ShowError is a copy of part of WinErr for PB CC.
I found by experiment that the On Error works TOO well - intermittently
gives "Error 0 = The operation completed succesfully".
Using "If ErrApi then BtmLneErr" does not do this.
But neither method replaces or precedes the Window messages about
"... illegal operation and will be shut down" which is precisely the
object of the excercise.
'_______________________________________________________________________

Function ShowError (ByVal x&) As String
 If ErrApi Then ShwErrErr
  FormatMessage %FORMAT_MESSAGE_FROM_SYSTEM, ByVal %NULL, x&, %NULL, errbfr, SizeOf(errbfr), ByVal %NULL

  If Len(errbfr) Then
    Function = "Error " & Format$(x&) & " = " & errbfr
  Else
    Function = "Unknown error code: " & Format$(x&)
  End If
 Exit Function
ShwErrErr:
 MsgBox(showError(ErrApi)+" in WPtester, ShowError")
 End Function      '(ShowError)
'_______________________________________________________________________

Function BottomLine (ByVal cL&) As Long
 If ErrApi Then BtmLneErr
' On Error Goto BtmLneErr
 While cL&<dtlCnt& And Val(Left$(IstLst$(cL&+1),4))=Val(Left$(IstLst$(cL&),4))
  Incr cL&
  Wend              'Establish the LAST line (on screen) of the
 Function=cL&       'order item per cL& (see sub SetFirstLastList
 Exit Function      'above)
BtmLneErr:
 MsgBox(showError(ErrApi)+" in WPtester, BottomLine")
 End Function      '(BottomLine)

'_______________________________________________________________________


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[Michael Mattias]

I had the same problem once. Did some reading and realized not all API calls Set "Last Error" or provide a value to the GetLastError call (which I assum is the underlying function servicing the PB ERRAPI function).

For calls which don't, you can use the SetLastError API to tell Windows what to look for. But unless you know which APIs the PBRT calls, in what order, this may get you precisely nowhere.

MCM

[DienyduToit]

Thanks, Michael. In any event my code as posted would not be very
useful since the ErrApi has to be present upon entry, and will
definitely have arisen in a preceding sub or function.

One could also try

On error goto xxxErr

and there ---

xxxErr:
if ErrApi=0 then resume dword abc

--- but to maintain the dword (abc) makes it totally
impracticable, also labeling EVERY LINE of code!!!

Pity; the error in text form would be extremely useful to those
who can't make sense of the register values/stack dumps etc.
provided with the Windows ultimati.

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