File Read/Write problems
lazarus / 9-Editor

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forlornity · 2008-01-20 21:44

Hey again, I've got a problem writing to files (and possibly reading
from, I can't tell as I haven't written it yet ), whenever I try and
read from I file I have supposedly written to it outputs junk.
The junk is the same for every variable I store in the file.
The code is as follows:
Code: [Select]procedure TServerConfigForm.FormShow(Sender: TObject);
var
   PZCSettings:TPZCSettings;
begin
   AssignFile(SettingsFile, 'settings.wtf');
   If not fileexists('settings.wtf') then begin
      ReWrite(SettingsFile);
   end;
   Reset(SettingsFile);
  
   While not eof(SettingsFile) do begin
      Read(SettingsFile, PZCSettings);
      HostEdit.Text:=PZCSettings.Server;
      UserEdit.Text:=PZCSettings.UserName;
      PasswdEdit.Text:=PZCSettings.Password;
   end;
   CloseFile(SettingsFile);
end;

procedure TServerConfigForm.ApplyButtonClick(Sender: TObject);
var
   PZCSettings:TPZCSettings;
begin
   PZCSettings.Database:=DatabaseEdit.Text;
   PZCSettings.Server:=HostEdit.Text;
   PZCSettings.UserName:=UserEdit.Text;
   PZCSettings.Password:=PasswdEdit.Text;
  
   ReWrite(SettingsFile);
   Write(SettingsFile, PZCSettings);
   CloseFile(SettingsFile);
   ServerConfigForm.Close;
end;

Also, the type definition is
Code: [Select]TPZCSettings = record
      Server:String;
      UserName:String;
      Password:String;
      Database:String;
  end;

When I try and read from the file it gives a load of nonsense "
ð­º
ð­º
ð­º
ð­º
ð­º!"

Anyone able to tell me what's wrong?

Thanks, Forlornity.

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theo · 2008-01-20 22:09

If you have AnsiString on (default, $H+) then your record contains 4
pointers.
You can check this with: SizeOf(TPZCSettings) which will be 16 in your
case on 32bit Machine (4*4 Byte).
You save these Pointers, not the content of the Strings.
What you can do is:
  TPZCSettings = record
      Server:String[20];
      UserName:String[20];
      Password:String[20];
      Database:String[20];
  end;  

These Strings will be written afaik and SizeOf(TPZCSettings) should
return 84.

You'd better use TIniFile for this purpose, which handles AnsiString
too.

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forlornity · 2008-01-21 00:42

Thanks man, setting the string length did the trick (as I'm sure is
obvious to the more experienced).
I expected it would be something similar to this as it was throwing up
strange errors (the same type I get when attempting to read past the
end of an array for instance).
Again, thanks for the info, Forlornity