Using labels to debug

[Gösta H. Lovgren-2]

The

#Debug Display On '<<<<<<<<<<<<<<< Remember to turn off for production code

is really great for picking up Bounds and other errors. It tells which sub, function, etc the error occurred in. Far far better than the gpf's we used to get.

However if the error occurs inside a long Sub, ... or deep within macros, or a long loop, or ... it can still be difficult to pin down. Not nearly as hard as before the Debug Display but still ...

Anyway here's a handy tip for further narrowing down the vexious culprit: At various points in the suspect code put line numbers (or labels), then when the error msg comes up it will say " ## Error after Line 1000" (or whatever thelast label was.

Function Foo() As Long 'tip o the derby to 
1000:     'Mile marker Id
  Call Complicated_Sub_Full_of_Macros
After_Complicated:   'Mile marker Id
  Call Macro
After_Macro:  'Mile marker Id
  Call Another_Sub
1300:      'Mile marker Id
  Call Macro
1400:  'Mile marker Id
'...  
End Function

Now when the errror trips, it will say "## Error ocurred after "After_Complicated" or "after 1300" or whatever Mile Marker that has been inserted set. Rather than just "After Foo".

================================
"You cannot depend on your eyes
when your imagination
is out of focus."
Mark Twain
================================

[John Gleason]

Thank you sir, I'll be making use of that for sure I'd bet.

[Paul Dixon]

Gösta,

At various points in the suspect code put line numbers

Why not write a small program which inserts a line number in every line of your code:

'PBCC5 program
FUNCTION PBMAIN () AS LONG

OPEN "MyProg.bas" FOR BINARY AS #1 'could use COMMAND$ to get the name so the .BAS file can just be dropped on the exe
GET$ 1,LOF(1),prog$                'get the source code
CLOSE #1

count&=PARSECOUNT(prog$,$CRLF)     'split into lines
DIM a$(1 TO count&)
PARSE  prog$, a$(), $CRLF

FOR r& = 1 TO count&               'add a line number to each line
    a$(r&)=RIGHT$("     " + TRIM$(STR$(r&))+" ",6)+a$(r&)
NEXT

prog$=JOIN$( a$(),$CRLF)           'reassemble the program

OPEN "MyProgX.bas" FOR BINARY AS #1
PUT$ 1,prog$                       'save the new, line numbered source file
SETEOF #1
CLOSE #1

END FUNCTION

It could be rewritten to suit your own use.
For example you could extract the file name to add the numbers to from COMMAND$ instead of specifying it in source code.
That way you can drag and drop a source file onto the line numbering .EXE.
You could also rewrite the same filename rather than giving it a new name.

Paul.

[Michael Mattias]

>Why not write a small program which inserts a line number in every line of your code:

That's pretty much what compilers which support a integrated stepping debugger do. During compilation they build a table referencing source code line to generated code offset. Then when running, they check the current instruction pointer, look up the referenced source code line and change the user display to show that as the executing line.

They also build a cross reference between user variables ("symbols") and the address of that variable, which allows for monitoring of "watch" items.

Not terribly important to this problem but I thought someone might find it interesting.

MCM

[Marco Pontello]

For anyone interested:

Source Code - Add line numbers to a PB source

I used it various time in the past. May require some minor modifications for the latests compilers versions.

Bye!

[Gösta H. Lovgren-2]

Gösta,

At various points in the suspect code put line numbers

Why not write a small program which inserts a line number in every line of your code:
l.

Fine idea, Paul. Or mayb Marco's code. Not that I'd ever need it, of course {laughing}. But it seems for a long complicated program with a difficult bug a 'Mile Marker' could be inerted before every line, saved as "Bug_Zapp er.bas" (ditto DLL's) and then run. That way original code doesn't get all cluttered up.

Thank you sir, I'll be making use of that for sure I'd bet.

I just lucked on to it myself. Not a new idea though, I guess (see Marco's post).

[Michael Mattias]

For problems resulting in a protection fault or other program termination, TRACE is a tremendous tool. It tells you the last procedure your program entered before termination.

Once you know WHERE the program got to, TRACE PRINT statements can be inserted to check the values of suspect variables.

"Really big" procedures? Throw in some labels every ten lines. TRACE reports every time you pass a label, too.

Better still, use 'many small' instead of 'few large' procedures. While I like to do this for maintenance and testing reasons, it is a boon when using TRACE to debug a problem.

I guess what I am saying here is, sure seems some folks are spending a lot of time reinventing the TRACE wheel.

I'm also saying, "How am I going to test and debug this application?" is something you should ask yourself - and answer - BEFORE you write that first line of code.

MCM

[Michael Mattias]

>is really great for picking up Bounds and other errors

How soon we^H^HI forget.... TRACE automatically shows your bounds violations without doing anything special...

' test_trace.bas
' 06.25.09
' PB/WIN 9.0.1
#COMPILE EXE
#DIM     ALL
#DEBUG    ERROR ON
#TOOLS ON


FUNCTION GetValue (Z() AS LONG) AS LONG
    LOCAL UB AS LONG
    LOCAL W  AS LONG, E AS LONG
    
    UB = UBOUND(Z,1)+ 1
Get_W:
    W  = Z(UB)
ASSIGN_FUNCTION:
    FUNCTION =  W
END FUNCTION

FUNCTION PBMAIN () AS LONG
    
  TRACE NEW "test_trace_log.txt"
  
  TRACE ON
  
  CALL RealMain

  TRACE OFF
  TRACE CLOSE
END FUNCTION

FUNCTION RealMain () AS LONG
    LOCAL X() AS LONG, Q AS LONG
   
My_REDIM:
    REDIM X(10)
CALL_GetValue:
    Q = GetValue (X())

RealMain_Exit:
    FUNCTION = Q 
   
END FUNCTION

Trace Begins...
 REALMAIN()
 MY_REDIM
 CALL_GETVALUE
  GETVALUE(1244496)
  GET_W
  Error 9 was generated in this thread
  ASSIGN_FUNCTION
  GETVALUE Exit
 REALMAIN_EXIT
 REALMAIN Exit
PBMAIN Exit

[Cliff Nichols]

Trace and other debug tools usually do more than enough for me to find something I did not think of, and fix it.

However larger projects, errors found (As we all well know) could arise LONGGGGGggg after the actual code that caused the error.

Also, the debugger is of no help when code you compiled as exe, debugged, and then turned into a Dll because you can not debug the dll.

Thats why "Real Men" build their own debugging routines.
RunTime Debug and Error Handling Part I - Find that elusive bug
RunTime Debug and Error Handling Part II - Find that elusive bug
and soon to be Part III, but thats when I saw Gosta's post about line numbers (and although already implemented) it reminded me of an idea I had for inserting these unique (and yes each label has to be unique) label without needing to precompile (IE: "Compile" once to add line numbers, and then really compile). So I am holding off on Part III until I touch-base with line numbers again.

Overkill??? Maybe so, but sure is saving me with code I wrote YEARS ago and had no clue that I made a

[Michael Mattias]

Also, the debugger is of no help when code you compiled as exe, debugged, and then turned into a Dll because you can not debug the dll.

I think you meant...

" Also, the stepping debugger is of no help when code you compiled as exe, debugged, and then turned into a Dll because you can not use the stepping debugger to debug the dll.

Please do not give 'newbies' the idea that that only way to 'debug' a program is to use the stepping debugger!

I'll leave out the obvious... no I won't:

I guess maybe that code in the EXE was not debugged all that well before it was moved to a DLL, huh?



MCM

[Cliff Nichols]

It also brings up a thought of how PB shows you line #'s in the editor and if I can get those values at compile time to nail down the row????

[Cliff Nichols]

I think you meant...
Quote:
" Also, the stepping debugger is of no help when code you compiled as exe, debugged, and then turned into a Dll because you can not use the stepping debugger to debug the dll.
Please do not give 'newbies' the idea that that only way to 'debug' a program is to use the stepping debugger!

Ok, I will bite, and ask, just HOW do you debug a dll (either your own, or one mapped into your process???)

I will agree to the STEPPING part, but if there is a way to debug a dll itself, then call me a newbie

I guess maybe that code in the EXE was not debugged all that well before it was moved to a DLL, huh?

Well all I did was uncomment compiler code for DLL and comment out compiler code for EXE (so no copy-paste errors) so you tell me where I went wrong using the tools I had, and test as well as I could and no errors, so the DLL should ALSO have no errors????

Either wayz, Gosta's post was something that not many people know

Anyway here's a handy tip for further narrowing down the vexious culprit: At various points in the suspect code put line numbers (or labels), then when the error msg comes up it will say " ## Error after Line 1000" (or whatever thelast label was.

A helpful tip for both newbies and old warhorses alike (Heck even I missed this one till ripping my hair out over a "BUG" that I wrote 5 years ago, and about to give up when I found I could "Mark" my code to help me narrow in)

Maybe just "Good Timing" on Gosta's part, but it prompted me to research more on how to possibly debug what "You did NOT plan for, but it DID occur, and now I have to FIND it and fix it"

Thank you Gosta for a subtle nudge, it went a long way to something I would soon forget if I had not looked into it.

[Gösta H. Lovgren-2]

Maybe just "Good Timing" on Gosta's part,

Rather than "good timing", I'd rather think the minds of real men travel in the same channel.

=======================================================
"A narcissist is someone better looking than you are."
Gore Vidal
=======================================================

Note - Gore Vidal disgusts me, but that was a good line.

[Patrice Terrier]

The zTrace utiliity could also help debugging existing code.

...

[Michael Mattias]

Ok, I will bite, and ask, just HOW do you debug a [procedure in a] dll

Ok, I will bite back...

• Predict the output based on input and compare
• Write log files
• Send display messages to STDOUT or in a MSGBOX to check status codes or intermediate results
• TRACE PRINT
• Interrogate return codes from function calls; check system ERR and/or OBJRESULT values after perfoming operations which may result in same.

Works here.

Better still, have a plan to test and debug before writing the first line of code.

[Cliff Nichols]

Ok, I will bite back...

• Predict the output based on input and compare
• Write log files
• Send display messages to STDOUT or in a MSGBOX to check status codes or intermediate results
• TRACE PRINT
• Interrogate return codes from function calls; check system ERR and/or OBJRESULT values after perfoming operations which may result in same.

Works here.

Better still, have a plan to test and debug before writing the first line of code.

And here I thought you might have some technique for debugging a DLL that had already been Debugged as an EXE. All of the above is what I already do.

There is no "Silver Bullet" but it sure would be nice to build a wooden one

[Michael Mattias]

And here I thought you might have some technique for debugging [a procedure in]a DLL that had already been Debugged [when in] an EXE

If a procedure has been debugged, it does not make any difference if it is packaged into an EXE or DLL.

This is an equation suitable for the new BIT variable type: either the procedure has been debugged or it hasn't.

MCM

[Gösta H. Lovgren-2]

Wheel Reinvention

Just for something to do today:

'

'
' *******************************************************
'
'Adds line numbers to existing code and creates a new .bas file
'  Useful if a program is GPF'ing. The error msg will indicate
'  the last line number that executed okay.
'
'********* Notes  **************
'Does not add line numbers to Macros (they don't like them)
'  Yields a 'Duplicate Line number error if a Macro is referenced
'  more than once  
'Won't affect/change existing program. It creates a New program (See Destination File)
'  Easiest to just Browse for a Source file and click Big Blue Button.
'  Then load Destination file in your Editor (hope it's JFP) and run from
'  there.
'Doesn't do great deal of Error checking, so it's on you if you change defaults
'Colors are due to an Italian/Mexican/Jamican mix girlfriend I had when young
'  who "influenced" me. Change to taste.
'Uses a font called "Bickley Script" you most likely don't have.
'  Change to an appropriate font you do have (I like Bickley. I once dated a college 
'  girl with nice handwriting.)
'
'
'
' *******************************************************
'
'PBWIN 9.01 - WinApi 05/2008 - XP Pro SP3
#Dim All 
#Compile Exe  
#Optimize SPEED
#Debug Display On'off for production code
 
' Includes
' *******************************************************
'
#Include "WIN32API.INC"
#Include "COMDLG32.INC"
#Include "InitCtrl.inc"
 'these next included files needed for button colors can be found here: 
 'http://www.powerbasic.com/support/pbforums/showthread.php?t=38904
#Include "C:\Only_My_Programs\Include Files\ButtonPlus.bas"
#Resource "C:\Only_My_Programs\Include Files\ButtonPlusDemo.pbr"
 
'
' Globals
' *******************************************************
'
Global hdlg As Dword                
Global g_Dlg_ht, g_Dlg_Wd As Long 'Global in case want to use in Controls
'
' Program Id's
' *******************************************************
'
%Source_File_Id = 1000     
%Browse_for_Source_Id = 1002
%Destination_File_Id = 1010
%Browse_for_Destination_File_Id = 1012
%Start_With_Number = 1014
%Fire_Id = 1100
%Exit_Btn_Id = 10000
' 
'Macros
' *******************************************************
'
Macro Common_Locals 'Macro easier than retyping and maintains coding consistency
  Local clor, Text_color, tb_wd, Id, Stile, Row, col, ht, wd, Longest,ctr, ln, ln1, i As Long
  Local fnum, Starting_Number As Long
  Local  t, tmp(), src, dest, fil, l, s As String                                                           
  Local f_Script, f_Consolas As Dword
'  Local Btn_Text_Color, Btn_Face_Color
  Font New "Bickley Script", 20 To f_Script
  Font New "Consolas", 12 To f_Consolas
End Macro  
'
Macro Draw_Textbox
  Wd = 100
  Ht = 40
  Text_Color = %Black
  Select Case Id
    Case %Source_File_Id     
      clor = %Blue
     Text_Color = %White
    Case %Destination_File_Id
      clor = %Green
    Case %Start_With_Number
      Clor = %Yellow
  End Select
 
  Control Add Label, hdlg, Id + 1, s$ + "  ", col, Row, wd, ht, %ss_right       
  Control Set Font hdlg, Id + 1, f_Script
  Control Set Color hdlg, Id + 1, Text_Color, clor
 
  Control Add TextBox, hdlg, Id, s$, col + wd + 10, Row, tb_Wd, ht       
  Control Set Font hdlg, Id, f_Consolas
  If Id = %Source_File_Id Then Id = %Browse_for_Source_Id'add browse button
  If Id = %Destination_File_Id Then Id = %Browse_for_Destination_File_Id
  If Id <> %Start_With_Number Then
     Control Add Button, hdlg, Id, "Browse", col + wd + 10 + tb_wd + 10, Row, wd, ht       
     Control Set Font hdlg, Id, f_Script                 
     ButtonPlus hDlg, Id, %BP_Face_COLOR, Clor
  End If   
 
'  End If
End Macro 
'
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''   
'
'------------------------------------------------------------------------------
' Browse for start-folder
' taken from Examples\FileFind.bas
'------------------------------------------------------------------------------
Function GetFolder (ByVal hParent As Dword) As String
    Local PathID As Dword
    Local bInf As BROWSEINFO
    Local szPath As Asciiz * %MAX_PATH
    bInf.hWndOwner = hParent 'Set some properties for the BFF dialog
    bInf.ulFlags   = %BIF_RETURNONLYFSDIRS Or %BIF_DONTGOBELOWDOMAIN
    bInf.lpszTitle = VarPtr(szPath)
    PathID = SHBrowseForFolder(bInf) 'Show the Browse-For-Folder dialog
    If PathID Then
        If SHGetPathFromIDList(ByVal PathID, szPath) Then
            Local gStartPath$
            gStartPath  = Extract$(szPath, Chr$(0))
            Function   = gStartPath
        End If
        CoTaskMemFree PathID 'Free allocated memory
    End If
End Function
'------------------------------------------------------------------------------
'
Sub Add_Line_Numbers
   common_Locals                
   Control Get Text hdlg, %Source_File_Id To src$ 
   If src$ = "Source file" Then
     ? src$,, "Error - No source file chosen"
     Exit Sub
   End If
'
   Control Get Text hdlg, %Destination_File_Id To dest$ 
   If Trim$(dest$) = "Destination" Then
     ? dest$,, "Error - No Destination file chosen"
     Exit Sub
   End If                             
'
   Control Get Text hdlg, %Start_With_Number To s$ 
   Replace "," With "" In s$
   Starting_Number = Val(s$)
 
   fnum = FreeFile
    Open Src$ For Binary As fnum
     ln = Lof(fnum)   
   t$ = Space$(ln)'create a space to put the file
   Get fnum,,t$  'put the file in the space
   Close fnum 
    ctr = ParseCount(t$, $CrLf) 
      Dim tmp$(ctr)
    Parse t$, tmp$(), $CrLf 
    If Starting_Number + UBound(tmp$()) > 65500 Then
      ? s$,,"Error, Starting number too big"
      Exit Sub
    End If
 
    Open dest$ For Output As #fnum 
    Local macro_flag, Continuation_Flag As Long
    For ctr = 1 To UBound(tmp$())
'      If Left$(Trim$(tmp$(ctr)), 1) = "'" Then Iterate For 'skip remarks
'      If Trim$(tmp$(ctr)) = "" Then Iterate For 'skip blank lines
'      Print #fnum, tmp$(ctr)    
      s$ = Trim$(tmp$(ctr))                        
 'No line numbers on macro definitions 
      If Left$(s$, 5) = "Macro" Then  macro_flag = 1
      If Left$(s$, 9) = "End Macro" Then 
         macro_flag = 0
        Print #fnum, tmp$(ctr)
        Iterate For
      End If           
 
      If macro_flag = 1 Then 
        Print #fnum, tmp$(ctr)
        Iterate For
      End If  
 
      s$ =  Using$("######  ", Starting_Number)
      If Continuation_Flag = 0 then
         Print #fnum, s$ & tmp$(ctr)
        Else 
         Print #fnum, tmp$(ctr)
      End If   
      Control Set Text hdlg, %Source_File_Id, s$ & tmp$(ctr) 'just to watch
      Incr Starting_Number
 
      Continuation_Flag = InStr(tmp$(ctr), " _")
    Next ctr 
    Close #fnum
End Sub
'
' Callbacks
' *******************************************************
'
CallBack Function PBMain_Processor              
  Common_Locals                                           
  Select Case CbMsg     'This is TO determine the message TYPE 
     '       
     Case %WM_INITDIALOG'<- Initialiaton when the program loads 
     '
     Case %WM_SYSCOMMAND 'Traps Any Alt key but only F4 closes              
     '
     Case %WM_COMMAND  'This processes command messages
       Select Case CbCtl
     '    Case %Id_Show_Result_Btn 
     '       Control Get Text CbHndl, %Id_Sample_Textbox To l$
     '         ? l$, , FuncName$
         '
         Case %Source_File_Id
         '
         Case %Browse_for_Source_Id', %Browse_for_Destination_File_Id
             OpenFileDialog (hdlg, _            ' parent window
                         "Choose the File to add line numbers to", _       ' caption
                         fil$, _            ' filename
                         "", _    ' start directory
                         "", _        ' filename filter
                         "bas", _  ' default extension
                         ctr _    ' flags
                         )
            Control Set Text hdlg, %Source_File_Id, fil$          
                 i = InStr(-1, fil$, "\") 'Create temporary file name
                 If i Then
                   fil$ = Left$(fil$, i) & _
                          "Numbered_" & _
                         Right$(fil$, Len(fil$) - i)
'                 ? fil$         
                 End If
            Control Set Text hdlg, %Destination_File_Id, fil$          
         '
         Case %Fire_Id
           Call Add_Line_Numbers
 
         '
         Case %Exit_Btn_Id
           Select Case CbCtlMsg        
              Case 0
                Dialog End CbHndl 'Applikation beenden
           End Select
       End Select
  End Select
End Function
'                           
'
' *******************************************************
'
Function PBMain
  Common_Locals
 'starting values
   Stile = Stile Or %WS_CAPTION
   Stile = Stile Or %WS_SYSMENU
   Stile = Stile Or %WS_THICKFRAME 
   Stile = Stile Or %WM_HELP 
   Stile = Stile Or %WS_Border  'doesn't do anything
  g_Dlg_ht = 300
  g_Dlg_Wd = 1000
  tb_wd = g_Dlg_Wd - 250
  'Dialog Font "Consolas", 72 ' Big Unicodes
  Dialog New Pixels, hdlg, "Line Numbering Addition", , , g_Dlg_Wd, g_Dlg_ht, Stile To hdlg 'centered
  Dialog Set Color hdlg, -1, &hff00ff
  '
  Row = 10
  col = 10
  Id = %Source_File_Id
  s$ = "Source file"
  Draw_Textbox
  '
  Row = Row + ht + 10
  s$ = "Destination"
  Id = %Destination_File_Id
  Draw_Textbox
  '
  Row = Row + ht + 10
  Id = %Start_With_Number
  s$ = "Starting #"
  Draw_Textbox
   Control Set Text hdlg, Id, Using$(" ###,### ",10000)
   ht = 50   
   Wd = g_Dlg_wd - 40
   col =  (g_Dlg_wd - wd) \ 2 
   Row = g_Dlg_ht - (Ht * 2.7) 'Just off bottom 
  Id = %Fire_Id 
  Control Add Button, hdlg, Id, _
     "Browse/Choose or Enter a Source file "  & $CrLf & _
     "and Click Here to create a Line Numbered file", _
      col, row, Wd, Ht * 1.5
     ButtonPlus  hdlg, Id, %BP_FACE_BLEND, 255 'truer color
     ButtonPlus hDlg, Id, %BP_Face_COLOR, %Blue
     ButtonPlus hDlg, Id, %BP_Text_COLOR, %White
    Control Set Font hdlg, Id, f_Script
   Row = g_Dlg_ht - Ht - 2 'Just off bottom
   Id =  %Exit_Btn_Id
  Control Add Button, hdlg, Id, "Abandon Ship", col, row, Wd, Ht
     ButtonPlus  hdlg, Id, %BP_FACE_BLEND, 255 'truer color
     ButtonPlus hDlg, Id, %BP_Face_COLOR, %Red
     ButtonPlus hDlg, Id, %BP_Text_COLOR, %White
 
    Control Set Font hdlg, Id, f_Script
 
     Dialog Show Modal hDlg   Call PBMain_Processor
End Function  'Applikation beenden
'

==================================
"A man with a new idea is a crank
until the idea succeeds."
Mark Twain
==================================