[Lazarus] LongString does not work?

[Jürgen Hestermann]

Am 2013-03-03 13:49, schrieb Xiangrong Fang:
> Hi Sven,
> {$mode objfpc}{$H+}
>   TConfiguration = packed record
>       DataFolder: string;
>   end;
> does not work, but:

A (Ansi)string in {$H+} mode is just a pointer (to the characters of the string). So sizeof(DataFolder)=4 (or 8) in all cases. There is no room for the string unless you configure it with SetLength(DataFolder,MaxPathLen). But even then the record does not store the characters. It only stores the pointer to the string:

DataFolder = pointer
DataFolder[1] = DataFolder^[1] = first character of the string.

There is an automatic dereferenciation that allows to write DataFolder[x] although the logic would require DataFolder^[1].



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