Convert String To Date catch EConvertError

[krull]

Hello again,

i have a new Program underway. It is a vocabulary tester. In the following procedure witch handles the random generator to find some Words out of the Stringgrid which have the correct Date value. So far so good. But if i run the program it gives me during runtime an EConvertError back, directly at a complex until statement. (line 30,37,46...).

Thanks

Code: Pascal  [Select][+][-]

1. procedure TForm3.BeginButtonClick(Sender: TObject);
2. label 3;
3. var some : TDateTime;
4. begin
5.   randomize;
6.   if (tryStrToDate(FromEdit.Text,some,'.')=false) and not (FromEdit.Text='now') and not (FromEdit.Text='all') then
7.   begin
8.     ShowMessage('Incorrect the Date-Time format. Format is DD.MM.YYYY.');
9.     Goto 3;
10.   end
11.   else if (tryStrToDate(ToEdit.Text,some,'.')=false) and not (ToEdit.Text='now') and not (ToEdit.Text='all') then
12.   begin
13.     ShowMessage('Incorrect the Date-Time format. Format is DD.MM.YYYY.');
14.     GoTo 3;
15.   end;
16.   if (EngDeuBox.Text='Eng->Deu') then
17.   begin
18.     if ((FromEdit.text='all') and (ToEdit.text='all')) or ((FromEdit.text='now') and (ToEdit.text='all')) or ((FromEdit.text='all') and (ToEdit.text='now'))then
19.     begin
20.       j:=1+random(Form1.VokabelGrid.RowCount-1);
21.       WordLbl.Caption:=Form1.VokabelGrid.Cells[0,j];
22.     end
23.     else if (FromEdit.Text='now') and (ToEdit.Text='now') then
24.     begin
25.     end
26.     else if (FromEdit.Text='now') and not (ToEdit.Text='now') then
27.     begin
28.       repeat
29.         j:=1+random(Form1.VokabelGrid.RowCount-1);
30.       until (Date>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(ToEdit.text));
31.       WordLbl.Caption:=Form1.VokabelGrid.cells[0,j];
32.     end
33.     else if not (FromEdit.Text='now') and  (ToEdit.Text='now') then
34.     begin
35.       repeat
36.         j:=1+random(Form1.VokabelGrid.RowCount-1);
37.       until (Date>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(FromEdit.text));
38.       WordLbl.Caption:=Form1.VokabelGrid.cells[0,j];
39.     end
40.     else if (tryStrToDate(FromEdit.text,some,'.')) and  (tryStrToDate(ToEdit.text,some,'.')) then
41.     begin
42.       if (StrToDate(FromEdit.text)>StrToDate(ToEdit.Text))then
43.       begin
44.         repeat
45.           j:=1+random(Form1.VokabelGrid.RowCount-1);
46.         until (StrToDate(FromEdit.Text)>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(ToEdit.text));
47.         WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
48.       end;
49.       if(StrToDate(FromEdit.text)<StrToDate(ToEdit.Text))then
50.       begin
51.         repeat
52.           j:=1+random(Form1.VokabelGrid.RowCount-1);
53.         until (StrToDate(ToEdit.Text)>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(FromEdit.text));
54.         WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
55.       end;
56.     end;
57.   end
58.   else
59.   begin
60.     if ((FromEdit.text='all') and (ToEdit.text='all')) or ((FromEdit.text='now') and (ToEdit.text='all')) or ((FromEdit.text='all') and (ToEdit.text='now'))then
61.     begin
62.       j:=1+random(Form1.VokabelGrid.RowCount-1);
63.       WordLbl.Caption:=Form1.VokabelGrid.Cells[1,j];
64.     end
65.     else if (FromEdit.Text='now') and (ToEdit.Text='now') then
66.     begin
67.     end
68.     else if (FromEdit.Text='now') and not (ToEdit.Text='now') then
69.     begin
70.       repeat
71.         j:=1+random(Form1.VokabelGrid.RowCount-1);
72.       until (Date>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(ToEdit.text));
73.       WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
74.     end
75.     else if not (FromEdit.Text='now') and  (ToEdit.Text='now') then
76.     begin
77.       repeat
78.         j:=1+random(Form1.VokabelGrid.RowCount-1);
79.       until (Date>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(FromEdit.text));
80.       WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
81.     end
82.     else if (tryStrToDate(FromEdit.text,some,'.')) and  (tryStrToDate(ToEdit.text,some,'.')) then
83.     begin
84.       if (StrToDate(FromEdit.text)>=StrToDate(ToEdit.Text))then
85.       begin
86.         repeat
87.           j:=1+random(Form1.VokabelGrid.RowCount-1);
88.         until (StrToDate(FromEdit.Text)>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(ToEdit.text));
89.         WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
90.       end;
91.       if(StrToDate(FromEdit.text))<=(StrToDate(ToEdit.Text))then
92.       begin
93.         repeat
94.           j:=1+random(Form1.VokabelGrid.RowCount-1);
95.         until (StrToDate(ToEdit.Text)>=StrToDate(Form1.VokabelGrid.Cells[2,j])) and (StrToDate(Form1.VokabelGrid.Cells[2,j])>=StrToDate(FromEdit.text));
96.         WordLbl.Caption:=Form1.VokabelGrid.cells[1,j];
97.       end;
98.     end;
99.   end;
100.   GroupBox1.Enabled:=false;
101.   GroupBox2.Enabled:=true;
102. 3:
103. end;
104.  

[Handoko]

Hello krull.

Can you please provide more information? What you want to do or maybe some screenshots.

I tried to run the code you provided, but I can't make it works, you did not provide the contents of the VokabelGrid.

It will be much better if you are willing to provide the whole source code. But if for some reasons you are not willing to publicize your project, you can make a test project that shows us the issue. Compress the source code including all the necessary files, except the exe and the lib folder. Zip them and attach it to this forum.

[marcov]

There is still a strtodate in there that can generate econversionerror.

[krull]

O.K. here the whole code espacally in Form3 there are still Building Sites.
Thank you for your help. I think i learn a lot in this Forum.

[Thaddy]

There is still a strtodate in there that can generate econversionerror.

I would be more worried about the randomize call....

[Handoko]

I put this:

Code: Pascal  [Select][+][-]

1. ShowMessage(Form1.VokabelGrid.Cells[2,j]);

just before the line that causes exception, and the result is an empty string. I enabled range check, but no out of bound error happened. Still testing. But one thing is sure, the code provide bad input for StrToDate. Because:

Code: Pascal  [Select][+][-]

1. StrToDate('');

will cause exception.

[Handoko]

More tests and I found that VokabelGrid.RowCount did not 'really' return the correct row count. I used this code:

Code: Pascal  [Select][+][-]

1.   for i := 0 to Form1.VokabelGrid.RowCount-1 do
2.     ShowMessage(Form1.VokabelGrid.Cells[2,i]);

By using the code above, I got the last row with empty cells.

After some inspections I think this is the culprit:

Code: Pascal  [Select][+][-]

1. // on TForm1.OnCreate
2.       VokabelGrid.Cells[0,j]:=first;
3.       VokabelGrid.Cells[1,j]:=second;
4.       VokabelGrid.Cells[2,j]:=third;
5.       VokabelGrid.InsertColRow(false,j+1);
6.       inc(j);

It inserts a row after cells update. It is wrong, it should be insert a row when needed.

[krull]

Good I try to eleminate this additional row. But with this are ten other faults opening.
For example in Form2 the entry for new Words (line 87) is throwing with GridExeptions.
And I don't find correct implementation.

[Thaddy]

You can also validate first. By using DateUtils.IsValidDate.... And get rid of the randomize in that spot.

[Handoko]

I tested the code again, sorry it has too much bugs.

You tried to add a new record after update an item. That is the issue in TForm2.Button1Click. The correct flow should be like this:

01. User provide a new item
02. Check if the item already existed
03. If yes then show an error and exit (I noticed you use goto 1)
04. If no then continue the the flow below
05. Add a new record
06. Update/save the record using the values provided by the user

What you did are not correct:
05. Update/save the record
06. Add a new record (to be used for future usage)

I want to try to fix the bugs, but it is easier to write from a fresh start.

Your code cannot run properly on countries outside yours. I saw you use a dot as date separator. But my country uses a minus sign as date separator. There are basically 2 ways to solve it. The easier way, I recommend you to put this line at the very beginning of the program.

Code: Pascal  [Select][+][-]

1.    DefaultFormatSettings.DateSeparator := '.';

Also here are some non-critical issues:

Code: Pascal  [Select][+][-]

1.       if something then
2.       begin
3.         Form1.VokabelGrid.cells[1,j]:=Form1.VokabelGrid.cells[1,j]+','+EditDeu.Text;
4.         Form1.VokabelGrid.cells[2,j]:=DateToStr(Date);
5.         GoTo 1;
6.         break;
7.       end;

Don't use break after goto statement. The break will never be executed.

It is not a sin using goto statement. But I recommend you to use Exit statement. It is less typing and more readable.

https://www.freepascal.org/docs-html/rtl/system/exit.html

[krull]

Thank you all,

I've got it now. The code wasn't so bugy. The only problem were (RowCount-1).