Some time ago I showed how to set up a directory in an application
window. This appears in Ex1 in CPTR on the SQLUG site. It might be
worth looking at that.
George
On 19 Nov 2005, at 04:42, James Hunkins wrote:
> Guys,
>
> I have hit a strange behavior with C68 in the qptr windows
> environment. Perhaps someone has some idea of what is going on. It
> has to do with trying to use menu structures for app windows.
>
> When I try to use the following structure for one of my app windows,
> it seems to be reserving the wrong size when I setup it up, causing
> problems with accesses to any app windows following the first use of
> the structure.
>
> static struct WM_menw mw0 =
> {
> ...
> }
>
> static struct WM_appw aw1 =
> {
> ...
> }
>
> static struct WM_appw aw2 =
> {
> ...
> }
>
> static struct WM_appl appl[4] = {(struct WM_menw *)&mw0, &aw1,
> &aw2,
> NULL};
>
> It draws OK but when I access the structure from the WM_appl_t part,
> it has problems.
>
> What I found is:
>
> sizeof(struct WM_menw) = 172 -> correct
> sizeof(struct WM_appw) = 104 -> correct
>
> &mw0 = 0x9da162 &aw1 - &mw0 = 0xAC = 172 -> correct
> &aw1 = 0x9da20e &aw2 - &aw1 = 0x68 = 104 -> correct
> &aw2 = 0x9da276
>
> ww.pappl->pappw[0] = 0x9da162 == &mw0 -> correct
> ww.pappl->pappw[1] = 0x9da1ca != &aw1 -> error
> ww.pappl->pappw[2] = 0x9da232 != &aw2 -> error
>
> I would have assumed that the struct WM_appl would be storing the
> true values for the addresses of mw0, aw1, and aw2. But as you can
> see, the values are different when I read them back.
>
> In fact, the difference between pappw[1] and pappw[0] = 0x68.
> Further tests show that no matter what I do, the values stored in the
> pappl structure always seem to be incremented by 0x68, no matter what
> the real address that each entry points to.
>
> In qptr_h:
> struct WM_appl
> {
> WM_appw_t *pappw;
> }
>
> It looks like this is actually a pointer as I would have expected.
>
> This would seem to be either a bug in C68 where C68 is overwriting
> the pointer values in the WM_appl structure based on the first entry
> and the standard space for struct WM_appw. Or it is something that I
> am just not understanding.
>
> Since the original data structure is reserving the correct spaces and
> there is no problem with that, my current work around is to save off
> some global variables pointing to &mw0, &aw1 and &aw2 and not rely on
> the ww.pappl-> entries.
>
> Any suggestions/comments?
>
> Thanks,
> jim
>
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