Digital Metaphors Report Builder 11.05: why my DELPHI code crashes without any error? - reportbuilder

Question

Now I build a template for our invoice printer.
But I do really not know, why it crashes without any error.
My goal is to separate the String ItemName at the ';' and print each part into a new line to a Memo1.
procedure DetailBeforeGenerate;
var
s1: String;
s2: String;
wordcount: Integer;
notelength: Integer;
begin
s1 := plPrintInvLine['ItemName'];
notelength := Length(s1);
while notelength > 0 do
begin
notelength := Length(s1);
wordcount := Pos(';' , s1);
s2 := Copy(s1, 0, wordcount-1);
Memo1.Lines.Add(s2);
Delete(s1, 0, wordcount);
end;
end;

Answer 1

See comments below regarding accessing index[0] in a string and thanks to David Heffernen and Ken White. BUT:
Looks like you've got an infinite loop in your code:
notelength := Length(s1);
while notelength > 0 do
begin
notelength := Length(s1);
wordcount := Pos(';' , s1);
s2 := Copy(s1, 0, wordcount-1);
Memo1.Lines.Add(s2);
Delete(s1, 0, wordcount);
end;
Delete(s1, 0, wordcount); Has no effect! Try it in Delphi debugger. Result? notelength is never decremented so you'll loop forever. ' Delete(s1, 0, wordcount);' does not blow up but neither does it delete. Use Delete(s1,1, wordcount) instead.
Index[0] in Delphi strings does not contain your character data - it's 'not accessible' according to the compiler, if you try compiling myString[0];
Also: the way your code is written, you MUST terminate with ';' or a string such as this:
s1 := 'mikey;was;here;a'; will loop infinitely on the last string after ';' ('a')
I also use ReportBuilder templates, etc: In Delphi itself you will not be able to compile MyString[0], but the copy and delete methods are protected from this error, (as David explained) however it appears from what I saw in the debugger that 'Delete(s1, 0, wordcount)' will not throw an exception but fails to delete. So I would not expect RBuilder to be any better, and perhaps worse - copy() may also be failing on string[0] in RAP.
RAP is NOT Delphi - it is a Runtime scripting environment that runs in your template, based on Object Pascal, but it does not support everything, and you cannot always expect it to behave exactly like Delphi.
BTW - ReportBuilder is now up to version 14.0X - if possible you should upgrade - there have been a lot of improvements in the RAP environment. In a later version your code might work OK or you'll get back an error message from RAP.
Also: If you want to debug in RAP it's not so easy. But to give you a clue as to where the error might be occurring, put a text label on your report and after each line of your code add
mylabel.caption:='statementxxx ran';
or
mylabel.caption:= myVariable.value;
Etc. That will give you a little ad hoc tracer - maybe show you where/why you failed, etc.

Answer 2

For all searching people: I found the solution with the excellent help of this community!
The working code looks like this:
procedure DetailBeforeGenerate;
var
S1: String;
S2: String;
wordcount: Integer;
notelength: Integer;
begin
S1 := plPrintInvLine['ArtName'];
notelength := Length(S1);
while (notelength > 0) do
begin
wordcount := Pos(';',S1);
S2 := Copy(S1, 1, wordcount-1);
if ( Pos(' ',S2) = 1 ) then Delete(S2, 1, 1);
Memo1.Lines.Add(S2);
Delete(S1, 1, wordcount);
notelength := notelength - wordcount;
end;
end;