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Author Topic: File not open??? Why?  (Read 1141 times)

OC DelGuy

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File not open??? Why?
« on: January 31, 2023, 03:19:34 am »
I just wrote this procedure  Why is the file "Not Open"?
Code: Pascal  [Select][+][-]
  1. Procedure WriteVillagedata;   // This will write the Data Structure to file.
  2.   Var
  3.     x, y : Integer;
  4.   Begin
  5.     Assignfile(FilenameOut, 'VillageData.txt');
  6.     Try
  7.       ReWrite(FilenameOut);
  8.       For x := 1 to recds do
  9.         Begin
  10.           WriteLn(FilenameOut, Villages[x].Name);            This is line 60 as referred to in the error message.
  11.           WriteLn(FilenameOut, Villages[x].Inn);
  12.           WriteLn(FilenameOut, Villages[x].Government);
  13.           WriteLn(FilenameOut, Villages[x].Population);
  14.           WriteLn(FilenameOut, Villages[x].Families);
  15.           WriteLn(FilenameOut, Villages[x].Farmers);
  16.           WriteLn(FilenameOut, Villages[x].Artisans);
  17.           WriteLn(FilenameOut, Villages[x].Laborers);
  18.           WriteLn(FilenameOut, Villages[x].Paupers);
  19.           For y := 1 to 3 do
  20.             Begin
  21.               WriteLn(FilenameOut, Villages[x].Gods[y]);
  22.               WriteLn(FilenameOut, Villages[x].Taverns[y]);
  23.               WriteLn(FilenameOut, Villages[x].Trade[y]);
  24.             end; {For y}
  25.           Close(FilenameOut);
  26.         End; {For x}
  27.     finally
  28.     end; {Try}
  29.   end; {Proc WriteVillagedata}
Free Pascal Lazarus Version #: 2.2.4
Date: 24 SEP 2022
FPC Version: 3.2.2
Revision: Lazarus_2_2_4
x86_64-win64-win32/win64

KodeZwerg

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Re: File not open??? Why?
« Reply #1 on: January 31, 2023, 03:40:11 am »
Try not to close the file in your loop, does it help?
Code: Pascal  [Select][+][-]
  1. Procedure WriteVillagedata;   // This will write the Data Structure to file.
  2.   Var
  3.     x, y : Integer;
  4.     FilenameOut: TextFile;
  5.   Begin
  6.     Assignfile(FilenameOut, 'VillageData.txt');
  7.     Try
  8.       ReWrite(FilenameOut);
  9.       For x := 1 to recds do
  10.         Begin
  11.           WriteLn(FilenameOut, Villages[x].Name);            This is line 60 as referred to in the error message.
  12.           WriteLn(FilenameOut, Villages[x].Inn);
  13.           WriteLn(FilenameOut, Villages[x].Government);
  14.           WriteLn(FilenameOut, Villages[x].Population);
  15.           WriteLn(FilenameOut, Villages[x].Families);
  16.           WriteLn(FilenameOut, Villages[x].Farmers);
  17.           WriteLn(FilenameOut, Villages[x].Artisans);
  18.           WriteLn(FilenameOut, Villages[x].Laborers);
  19.           WriteLn(FilenameOut, Villages[x].Paupers);
  20.           For y := 1 to 3 do
  21.             Begin
  22.               WriteLn(FilenameOut, Villages[x].Gods[y]);
  23.               WriteLn(FilenameOut, Villages[x].Taverns[y]);
  24.               WriteLn(FilenameOut, Villages[x].Trade[y]);
  25.             end; {For y}
  26.         End; {For x}
  27.     finally
  28.       Close(FilenameOut);
  29.     end; {Try}
  30.   end; {Proc WriteVillagedata}
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

jamie

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Re: File not open??? Why?
« Reply #2 on: January 31, 2023, 03:41:26 am »
Assign(...) instead of AssignFile?


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Bogen85

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Re: File not open??? Why?
« Reply #3 on: January 31, 2023, 03:44:58 am »
Assign(...) instead of AssignFile?

That is fine.

Code: Pascal  [Select][+][-]
  1. program wvd;
  2. {$mode objfpc}
  3.  
  4. Procedure WriteVillagedata;   // This will write the Data Structure to file.
  5.   Var
  6.     x, y : Integer;
  7.   FilenameOut: textfile;
  8.   Begin
  9.     Assignfile(FilenameOut, 'VillageData.txt');
  10.     Try
  11.       ReWrite(FilenameOut);
  12.       writeln(FilenameOut, 'text');
  13.     finally
  14.       close(FilenameOut);
  15.     end; {Try}
  16.   end; {Proc WriteVillagedata}
  17.  
  18. begin
  19.   WriteVillagedata;
  20. end.
  21.  

The above works, @KodeZwerg likely caught the problem, the close file being in the loop.

KodeZwerg

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Re: File not open??? Why?
« Reply #4 on: January 31, 2023, 03:54:16 am »
Maybe also his "FilenameOut" is wrong, since he not show, I added that on my own as local.
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

Thaddy

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Re: File not open??? Why?
« Reply #5 on: January 31, 2023, 05:52:50 am »
If it has to be old school, I would write it like so:
Code: Pascal  [Select][+][-]
  1. program wvd;
  2. Procedure WriteVillagedata;   // This will write the Data Structure to file.
  3.   Var
  4.     e:Integer;
  5.     FilenameOut: textfile;
  6.   Begin
  7.     Assign(FilenameOut, 'VillageData.txt');
  8.     {$push}{$I-  because we want to handle IOResult ourselves. This can be local}
  9.     ReWrite(FilenameOut);
  10.     e:= IOResult;// because IOResult gets cleared after access, store it!!
  11.     {$pop}
  12.     if e = 0 then Try
  13.       writeln(FilenameOut, 'text');
  14.     finally
  15.       flush(FilenameOut);
  16.       close(FilenameOut);
  17.     end else writeln ('error: ', e);
  18.   end;
  19. begin
  20.   WriteVillagedata;
  21. end.
I suspect that when examining IOResult the original code will show an error...
Also, just to be sure, call flush() before closing.
Anyway, if you pull in classes better to use a TFileStream and if you pull in sysutils, use exception objects.
Assign() - or the hidious AssignFile(), which is mode dependent - does not cause IOResult to be set, but rewrite() will... And now we handle 103 the proper way.
Errors are here: https://www.freepascal.org/docs-html/rtl/system/ioresult.html

Note, of course Bogen85's example code on which I based this, also works in most cases, I just added error handling the olden way.
« Last Edit: January 31, 2023, 06:15:55 am by Thaddy »
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KodeZwerg

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Re: File not open??? Why?
« Reply #6 on: January 31, 2023, 06:18:07 am »
If it has to be old school
I doubt that, so I show a more modern way:
Code: Pascal  [Select][+][-]
  1. procedure WriteVillagedata;   // This will write the Data Structure to file.
  2. var
  3.   x, y: Integer;
  4.   sl  : TStrings;
  5. begin
  6.   sl := TStringList.Create;
  7.   try
  8.     for x := 1 to recds do
  9.     begin
  10.       sl.Add(Villages[x].Name);
  11.       sl.Add(Villages[x].Inn);
  12.       sl.Add(Villages[x].Government);
  13.       sl.Add(Villages[x].Population);
  14.       sl.Add(Villages[x].Families);
  15.       sl.Add(Villages[x].Farmers);
  16.       sl.Add(Villages[x].Artisans);
  17.       sl.Add(Villages[x].Laborers);
  18.       sl.Add(Villages[x].Paupers);
  19.       for y := 1 to 3 do
  20.       begin
  21.         sl.Add(Villages[x].Gods[y]);
  22.         sl.Add(Villages[x].Taverns[y]);
  23.         sl.Add(Villages[x].Trade[y]);
  24.       end; {For y}
  25.     end; {For x}
  26.     sl.SaveToFile(ExtractFilePath(ParamStr(0)) + 'VillageData.txt'); // <<<--- I strongly suggest to add a path infront of filename
  27.   finally
  28.     sl.Free;
  29.   end;
  30. end;
Ofc the record stuff I can't check but at least you see some logic.
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

Thaddy

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Re: File not open??? Why?
« Reply #7 on: January 31, 2023, 06:30:09 am »
Yup, something like that (missing exception handling, though?)
Note I wrote "old school", but there is relevance on memory or hardware starved systems that do not use classes or sysutils, like many embedded systems. It is more lightweight and also a bit more portable.
I would also use packed records and write an entry in one go. And of course  ;D count from zero  :D
« Last Edit: January 31, 2023, 06:39:09 am by Thaddy »
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KodeZwerg

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Re: File not open??? Why?
« Reply #8 on: January 31, 2023, 06:59:53 am »
Yup, something like that (missing exception handling, though?)
Uhm... the only "error handling" that comes in my mind would be to test if file exists, try to delete, when that succeed write it.
Do you have something different in your mind that I am currently not aware of?
Or you meant a seperate "try/except" around the SaveToFile() ?
As longer I think about, as more strange stuff come in my head  %) (I usual just let the class do the job...)

And of course  ;D count from zero  :D
Absolute! Thats why I noted:
Ofc the record stuff I can't check but at least you see some logic.
( Where I actual meant an array  :-[  :-X  :P )
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

egsuh

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Re: File not open??? Why?
« Reply #9 on: January 31, 2023, 07:55:08 am »
I believe the first answer is correct. File is closed after first x loop in the original example.

KodeZwerg

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Re: File not open??? Why?
« Reply #10 on: January 31, 2023, 08:07:49 am »
And of course  ;D count from zero  :D
Code: Pascal  [Select][+][-]
  1.     for x := 1 to recds do
Me dummy, ofc it should be written like that:
Code: Pascal  [Select][+][-]
  1.     for x := Low(Villages) to High(Villages) do
And he does not need to think about, or what does "recds" represent?

I believe the first answer is correct. File is closed after first x loop in the original example.
Yes.  8)
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

OC DelGuy

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Re: File not open??? Why?
« Reply #11 on: January 31, 2023, 08:38:51 am »
Try not to close the file in your loop, does it help?
Code: Pascal  [Select][+][-]
  1. Procedure WriteVillagedata;   // This will write the Data Structure to file.
  2.   Var
  3.     x, y : Integer;
  4.     FilenameOut: TextFile;
  5.   Begin
  6.     Assignfile(FilenameOut, 'VillageData.txt');
  7.     Try
  8.       ReWrite(FilenameOut);
  9.       For x := 1 to recds do
  10.         Begin
  11.           WriteLn(FilenameOut, Villages[x].Name);            This is line 60 as referred to in the error message.
  12.           WriteLn(FilenameOut, Villages[x].Inn);
  13.           WriteLn(FilenameOut, Villages[x].Government);
  14.           WriteLn(FilenameOut, Villages[x].Population);
  15.           WriteLn(FilenameOut, Villages[x].Families);
  16.           WriteLn(FilenameOut, Villages[x].Farmers);
  17.           WriteLn(FilenameOut, Villages[x].Artisans);
  18.           WriteLn(FilenameOut, Villages[x].Laborers);
  19.           WriteLn(FilenameOut, Villages[x].Paupers);
  20.           For y := 1 to 3 do
  21.             Begin
  22.               WriteLn(FilenameOut, Villages[x].Gods[y]);
  23.               WriteLn(FilenameOut, Villages[x].Taverns[y]);
  24.               WriteLn(FilenameOut, Villages[x].Trade[y]);
  25.             end; {For y}
  26.         End; {For x}
  27.     finally
  28.       Close(FilenameOut);
  29.     end; {Try}
  30.   end; {Proc WriteVillagedata}

Just seeing this, I'm pretty sure that's the problem.  This is one of those BRAIN-FART instances.  I just didn't notice it.  If I had noticed it before, I would not have posted this.  Of course it should be outside the loop, and that explains the runtime error.  It has to be happening during the second iteration of the x loop.  I'm on my Chrome book now, but I'll be back on the MSI tomorrow.
Free Pascal Lazarus Version #: 2.2.4
Date: 24 SEP 2022
FPC Version: 3.2.2
Revision: Lazarus_2_2_4
x86_64-win64-win32/win64

OC DelGuy

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Re: File not open??? Why?
« Reply #12 on: January 31, 2023, 08:57:42 am »
The above works, @KodeZwerg likely caught the problem, the close file being in the loop.
Yes.  I haven't checked it out, but I'm willing to bet it's the Close in the loop.  I'm also willing to bet that the runtime error is happening during the second iteration of the x loop.  Sorry guys, I just didn't notice.  I had a BRAIN-FART!!  When I check it tomorrow, I'm sure that will be the problem.
Free Pascal Lazarus Version #: 2.2.4
Date: 24 SEP 2022
FPC Version: 3.2.2
Revision: Lazarus_2_2_4
x86_64-win64-win32/win64

OC DelGuy

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Re: File not open??? Why?
« Reply #13 on: January 31, 2023, 09:05:37 am »
Maybe also his "FilenameOut" is wrong, since he not show, I added that on my own as local.
No, I don't believe so.  FilenameIn and FilenameOut are both declared as global variables.
Free Pascal Lazarus Version #: 2.2.4
Date: 24 SEP 2022
FPC Version: 3.2.2
Revision: Lazarus_2_2_4
x86_64-win64-win32/win64

KodeZwerg

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Re: File not open??? Why?
« Reply #14 on: January 31, 2023, 09:20:48 am »
Maybe also his "FilenameOut" is wrong, since he not show, I added that on my own as local.
No, I don't believe so.  FilenameIn and FilenameOut are both declared as global variables.
I believe that you did, its just the question as what  :-\
« Last Edit: Tomorrow at 31:76:97 by KodeZwerg »

 

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