How to insert data from a text file on lazarus?

[toyvoy]

How to insert data from a text file on lazarus? What is the code of it?

[Handoko]

Not very sure what you want to do, but maybe you're interested to read:
http://forum.lazarus.freepascal.org/index.php/topic,37766.msg254800.html#msg254800

File handling and database tutorial for beginner:
http://wiki.freepascal.org/File_Handling_In_Pascal
http://wiki.freepascal.org/Lazarus_Tdbf_Tutorial

[toyvoy]

I want to input some vocabulary to the program form a text file.
But the messages told me that it was wrong on the line( reset(f) )
I write my procedure as fellow.


procedure TForm1.Inputwords;
var f :textfile;
    n : integer;
begin
  n:=0;
   if Difficulty = 2 then begin
   assignfile(f,'Hard Mode.txt');
   reset(f);                                  <<<<<this line
   while eof(f)=false do begin
    n:=n+1;
    Readln(f,Word[2,n]);
   end;
   closefile(f);
  end;
end;                         

[Handoko]

What error did it say? Have you make sure the file exists on the correct directory?

[toyvoy]

The Messages:
Error: Wrong number of parameters specified for call to "reset"
Error: Found declaration: reset;
The file is in the same file where the program is.

[Handoko]

Can you please provide the whole source code and all the necessary files? Copy them to a new folder, except: *.exe, *.bak and lib folder. Compress the folder and send the zip file to this forum.

[toyvoy]

thanks for helping

[rvk]

So what does the Form1.Reset; function do??

When you call reset(f); in TForm1.Inputwords; it wants to call TForm1.Reset; and NOT the reset(f:file) for file-functions.

Rename the Form1.Reset to something else (like ResetGame) and that error-message goes away.

[toyvoy]

So what does the Form1.Reset; function do??

When you call reset(f); in TForm1.Inputwords; it wants to call TForm1.Reset; and NOT the reset(f:file) for file-functions.

Rename the Form1.Reset to something else (like ResetGame) and that error-message goes away.

sorry I'm so careless and thanks

[howardpc]

There was a British propaganda campaign in the 1940s called "Careless talk costs lives"...

Carelessness in programming leads to all kinds of bugs.
Careful naming can help avoid some of them.
Thus your global array word[] would be better named slightly differently, to avoid any confusion with the Word type denoting an unsigned integer.

[Thaddy]

Off/on topic: https://en.wikipedia.org/wiki/2003_attack_on_Karbala shows how carelessness can lead to casualties. (triggered by howardpc, dunno why I made the connection, just came to mind)..

[ASerge]

To @toyvoy.
A few comments on the source code.

1. Get rid of global variables, this is generally a "bad" style. At least move them to the private section of the TForm1. If you later want to create a second instance of the form, you do not have to double the global variables.

2. The word is not a very suitable name for variable. It hides the built-in type word. So if you use the note above and add the letter F to the field name (common practice), you get FWord (maybe even better name FWords).

3. In FormPaint the try finally construct is used incorrectly (for some reason, the popular error). You must protect the resource after its allocation. Those you need to do

Code: Pascal  [Select][+][-]

1. Instance := TSomeClass.Create;
2. try
3.   //Code with Instance
4. finally
5.   Instance.Free;
6. end;

i.e. not transfer the initialization after a try. In your case, for example, if an exception occurs during the execution of the constructor, then call of Instance.Free will, at best case, cause a nested exception, but if in the Instance (garbage on the stack) will be the address of the real object (the main form, for example ) then you spent a lot of time to find an error in the program.

4. The InputWords procedure. If you protect a memory leak when creating an object, then the system resource (file) is all the more in need of protection, i.e. use try finally.

Code: Pascal  [Select][+][-]

1. AssignFile(f, ...);
2. Reset(f);
3. try
4.   // Use file
5. finally
6.   CloseFile(f);
7. end;

5. Expression if SomeBool = False then (or if SomeBool = True then) look clumsy. It is better to use the natural if not SomeBool then (or if SomeBool then).

6. VisibleAll and InvisibleAll procedures better be merged into one like SetVisible(AVisible: Boolean), then inside you use Field.Visible: = AVisible (or := not AVisible), and call as SetVisible(True) or SetVisible(False).

7. For the case statement, it's better to place the operators below line of constant value, so when debugging, you'll see which case was selected.

And returning to the original question: with name conflicts, you can specify the required procedure using the module name, that is, specify System.Reset.

[RAW]

 

Code: Pascal  [Select][+][-]

1. Function LoadTextFile(strFile: String): String;
2.   Var
3.    fs    : TFileStream;
4.    str   : String;
5.    iBytes: Integer;
6.  Begin
7.   Result:= '';
8.    If Not FileExists(strFile) Then Exit;
9.  
10.   fs:= TFileStream.Create(strFile, fmOpenRead);
11.    Try
12.     SetLength(str, fs.Size);
13.     iBytes:= fs.Read(str[1], fs.Size);
14.  
15.     If iBytes = fs.Size Then Result:= str;
16.    Finally
17.     fs.Free;
18.    End;
19.  End;
20.  
21. Procedure TForm1.FormClick(Sender: TObject);
22.  Begin
23.   Memo1.Text:= LoadTextFile('I:\Temp\W7\Hard words.txt');
24.  End;

Code: Pascal  [Select][+][-]

1. Procedure TForm1.FormClick(Sender: TObject);
2.   Var
3.    str: String;
4.  Begin
5.   str:= LoadTextFile('I:\Temp\W7\Hard words.txt');
6.  
7.   If str <> '' Then ShowMessage(str);
8.  End;

[RAW]

OR....

Code: Pascal  [Select][+][-]

1. Function LoadTextFile(strFile: String; Out strOut: String): Boolean;
2.   Var
3.    fs    : TFileStream;
4.    str   : String;
5.    iBytes: Integer;
6.  Begin
7.   Result:= False;
8.    If Not FileExists(strFile) Then Exit;
9.  
10.   fs:= TFileStream.Create(strFile, fmOpenRead);
11.    Try
12.     SetLength(str, fs.Size);
13.     iBytes:= fs.Read(str[1], fs.Size);
14.  
15.     If iBytes = fs.Size
16.     Then
17.      Begin
18.       strOut:= str;
19.       Result:= True;
20.      End;
21.    Finally
22.     fs.Free;
23.    End;
24.  End;
25.  
26. Procedure TForm1.FormClick(Sender: TObject);
27.   Var
28.    str: String;
29.  Begin
30.   If LoadTextFile('I:\Temp\W7\Hard words.txt', str)
31.   Then ShowMessage(str);
32.  End;

[toyvoy]

3. In FormPaint the try finally construct is used incorrectly (for some reason, the popular error). You must protect the resource after its allocation. Those you need to do

Code: Pascal  [Select][+][-]

1. Instance := TSomeClass.Create;
2. try
3.   //Code with Instance
4. finally
5.   Instance.Free;
6. end;

i.e. not transfer the initialization after a try. In your case, for example, if an exception occurs during the execution of the constructor, then call of Instance.Free will, at best case, cause a nested exception, but if in the Instance (garbage on the stack) will be the address of the real object (the main form, for example ) then you spent a lot of time to find an error in the program.

Actually, I want to change the background image using FormPaint, but it falls obviously. Could you please explain more about it?
I don't know what this means :Instance := TSomeClass.Create;
and in this line [//Code with Instance]
what should I write in order to change the form's background with a jpg picture?
Thanks a lot for helping again!