On 09.02.2014 15:10, Fred van Stappen wrote:
> Date: Sun, 9 Feb 2014 13:08:16 +0100 > From: freepas...@ypa-software.de > To: fpc-pascal@lists.freepascal.org > Subject: Re: [fpc-pascal] High() and Low() for empty dynamic arrays > > Am 09.02.2014 13:05, schrieb Fred van Stappen: > > if length(MyArray) > 0 then > > for x := 0 to high(MyArray) do > > MyArray[x].Free; > > > > But, if i use : > > > > setlength(MyArray, 0) ; > > > > would it do the same job ? > > No. Your array contains only references to the objects. The references > where deleted, but the objects remain in memory without any destructor call. > > g > Michael OK, many thanks Michael. Hum, i have a dynamic array of threads. mythread.create has : FreeOnTerminate := True; So, when the thread terminate, it frees the memory too ? (yes/no).
Yes, that frees the complete class instance of the thread.
And it explain why i get a crash and error message if i try to do, for dynamic arrays of threads : > if length(MyArray) > 0 then > for x := 0 to high(MyArray) do > MyArray[x].Free; Because the threads are already freed (yes/no) ?
Exactly.
If so, how can i know if MyArray[x] was already freed ?
You can't. You must not access MyArray[x] anymore after the thread terminated.
When i use: if assigned(MyArray[x]) then MyArray[x].Free; It does not work.
Yes, because MyArray[x] is not modified when the thread destroys the class at the end of its life. It doesn't even know that there is a variable that points to the class (class instance variables are basically pointers to the real class instance data). Thus the MyArray[x] still contains the pointer to the class instance data, but the later was already destroyed, so it's no longer valid memory. So: don't touch it! ;)
Regards, Sven _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
