Delphi silently cropping string literals

Question

Delphi 2009 Win32.

The code below tries to add a 257 length string to a memo. It compiles and runs fine, but nothing is added to the memo.

Memo1.Lines.Add('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');

Looks like a compiler bug. Is it? Because if the string was 256 long, I'd get a compiler error and couldn't compile the app.

Any way to make the app break when the developer tries to do something like this?

I know I could split the string and make this code work, but my point is to prevent developers for using this invalid code without noticing.

Thanks

Answer 1

This is a Delphi 2009 bug with string literals, it should raise the same error as D2007.

Try latest version of Andreas IDE Fix pack, its supose to fix this bug. http://andy.jgknet.de/blog/?page_id=246

Answer 2

I agree with Gamecat, however if your dealing with a string that large, I would break it into muliple lines to assist in reading/editing.

if you are LITTERALLY trying to create 257 "a"'s then why not use the DupeString function in the StrUtils unit?

Memo.Lines.Add( DupeString('a',257) );

Much easier to read, and maintain later. If you are doing this in a loop and therefore are worried about performance, then assign the function result to a local variable and use the variable.

var
  sLotsOfAs : string;
  ix : integer;
begin
  sLotsOfAs := DupeString('a',257);
  for ix := 0 to 1000000 do
    Memo.Lines.Add( sLotsOfAs );
end;

Answer 3

The string literal can be only 255 characters long. Not sure why they kept this limitation. But you can solve it using multiple literals:

Memo1.Lines.Add('i have 128 chars' + 'i also have 128 chars').