[fpc-pascal] string memory management

[Sven Barth]

Am 19.04.2013 06:36, schrieb Xiangrong Fang:
> Hi All,
>
> I'm studying how pascal manages strings.  I wrote a simple test program:
>
> program stringtest;
> {$mode objfpc}{$H+}
> uses Classes, sysutils;
> function test: PString;
> var
>   s : string;
> begin
>   New(Result);
>   Result^ := FloatToStr(Random);
> //  s := FloatToStr(Random);
> //  Result := @s;
> end;
> var
>   i : Integer;
> begin
>   Randomize;
>   with TList.Create do try
>     for i := 0 to 9 do Add(test);
>     for i := 0 to Count - 1 do begin
>       WriteLn(PString(Items[i])^);
>     end;
>   finally
>     Free;
>   end;
> end.
>
> The program runs fine, but:
>
> 1. I don't know whether I have to MANUALLY free memory for these 
> strings to prevent leak?

The string types "String" (in mode $H+), "AnsiString" and 
"UnicodeString" are managed by the compiler/RTL. If you use a pointer 
type then you need to manage it yourself, thus you need to free the 
PString manually in this case.

Regards,
Sven
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