dev-cpp-users

[Dev-C++] conversion from void *

[Carlos d. M. <cg...@wo...>]

Hi:
I am learning windows programing, and in great proportion of the
examples I try to compile I get the error "ANSI C++ forbids implicit
conversion from `void *' in argument passing", many times due to the 0
value passed in functions like CreateWindowEx, in the last parameter,
what can I do for Mingw accept it? Some times I change 0 by NULL, but it
does not work always, in such cases, what can I do?

Thank you

Re: [Dev-C++] conversion from void *

[Hongli L. <h....@ch...>]

On Fri, 2002-07-05 at 21:11, Carlos Garc=EDa del Monte wrote:
> Hi:
> I am learning windows programing, and in great proportion of the
> examples I try to compile I get the error "ANSI C++ forbids implicit
> conversion from `void *' in argument passing", many times due to the 0
> value passed in functions like CreateWindowEx, in the last parameter,
> what can I do for Mingw accept it? Some times I change 0 by NULL, but it
> does not work always, in such cases, what can I do?
>=20
> Thank you
>=20

That parameter expects a pointer. 0 is an integer.
Since C++ is strict, you'll have to tell explicitly that 0 must be
treated as a memory location (pointer).
Something like this:
CreateWindowEx (foo, bar, (void *) 0);

Re: [Dev-C++] conversion from void *(and is neither void nor pointer)

[Carlos d. M. <cg...@wo...>]

Thanks, it works in some sites, but now I have found a place where it is a 0
in LoadImage, and it still says that, the parameter expected is an UINT, I do
everything but no way!

Here is the line:
    _class.hIcon = reinterpret_cast<HICON> (
        ::LoadImage (_class.hInstance,
    MAKEINTRESOURCE (resId),
    IMAGE_ICON,
    ::GetSystemMetrics (SM_CXICON),
    ::GetSystemMetrics (SM_CYICON),
    0));

I changed the first with  _class.hIcon = ::LoadIcon(_class.hInstance,
MAKEINTRESOURCE(resId)); and it says the same error. The same if I put 1-1
instead of 0, or if I declare a UINT var = 0; and write var. I use the
LR_DEFAULTSIZE flag and still says that.
Here is the code of the full function where the two lines still have error
are:

void WinClass::SetResIcons (int resId)
{
UINT zero = 0;
    _class.hIcon = reinterpret_cast<HICON> (
        ::LoadImage (
            _class.hInstance,
            MAKEINTRESOURCE (resId),
            IMAGE_ICON,
            ::GetSystemMetrics (SM_CXICON),
            ::GetSystemMetrics (SM_CYICON),
               0));
    // Small icon can be loaded from the same resource
    _class.hIconSm = reinterpret_cast<HICON> (
        ::LoadImage (
            _class.hInstance,
            MAKEINTRESOURCE (resId),
            IMAGE_ICON,
            ::GetSystemMetrics (SM_CXSMICON),
            ::GetSystemMetrics (SM_CYSMICON),
            0));
}

Borland 5.5 compiles fine, but I prefer Dev, it's more comfortable IDE than
those I found for Borland, with difference.

P.S.: Some times the error has lines where the error is unreadable characters.

Re: [Dev-C++] conversion from void *(and is neither void nor pointer)

[Napoleon A. <nah...@so...>]

Hi there,

There solution to your problem can be found at http://www.relisoft.com/forum
check Windows API Programming in C++. Below is an excerpt of the discussions
that went on.

..... The hInstance member of _class is a HANDLE (that is, _class is a
WNDCLASSEX, and WNDCLASSEX's 'hInstance' member is a HANDLE, not, as one
might guess from it's name, an HINSTANCE).  mingw does define HANDLE as a
pointer to void.  But LoadImage is looking for an honest-to-god HINSTANCE.

There is also a solution on the forumwhich works fine on Dev-C++.

Napoleon.
----- Original Message -----
From: "Carlos García del Monte" <cg...@wo...>
To: "dev-cpp-users-list" <dev...@li...>
Sent: Saturday, July 06, 2002 11:58 AM
Subject: Re: [Dev-C++] conversion from void *(and is neither void nor
pointer)


> Thanks, it works in some sites, but now I have found a place where it is a
0
> in LoadImage, and it still says that, the parameter expected is an UINT, I
do
> everything but no way!
>
> Here is the line:
>     _class.hIcon = reinterpret_cast<HICON> (
>         ::LoadImage (_class.hInstance,
>     MAKEINTRESOURCE (resId),
>     IMAGE_ICON,
>     ::GetSystemMetrics (SM_CXICON),
>     ::GetSystemMetrics (SM_CYICON),
>     0));
>
> I changed the first with  _class.hIcon = ::LoadIcon(_class.hInstance,
> MAKEINTRESOURCE(resId)); and it says the same error. The same if I put 1-1
> instead of 0, or if I declare a UINT var = 0; and write var. I use the
> LR_DEFAULTSIZE flag and still says that.
> Here is the code of the full function where the two lines still have error
> are:
>
> void WinClass::SetResIcons (int resId)
> {
> UINT zero = 0;
>     _class.hIcon = reinterpret_cast<HICON> (
>         ::LoadImage (
>             _class.hInstance,
>             MAKEINTRESOURCE (resId),
>             IMAGE_ICON,
>             ::GetSystemMetrics (SM_CXICON),
>             ::GetSystemMetrics (SM_CYICON),
>                0));
>     // Small icon can be loaded from the same resource
>     _class.hIconSm = reinterpret_cast<HICON> (
>         ::LoadImage (
>             _class.hInstance,
>             MAKEINTRESOURCE (resId),
>             IMAGE_ICON,
>             ::GetSystemMetrics (SM_CXSMICON),
>             ::GetSystemMetrics (SM_CYSMICON),
>             0));
> }
>
> Borland 5.5 compiles fine, but I prefer Dev, it's more comfortable IDE
than
> those I found for Borland, with difference.
>
> P.S.: Some times the error has lines where the error is unreadable
characters.
>
>
>
> -------------------------------------------------------
> This sf.net email is sponsored by:ThinkGeek
> Got root? We do.
> http://thinkgeek.com/sf
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
> https://lists.sourceforge.net/lists/listinfo/dev-cpp-users
>


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.372 / Virus Database: 207 - Release Date: 20/06/02

Re: [Dev-C++] conversion from void *(and is neither void nor pointer)

[Carlos d. M. <cg...@wo...>]

Yes, it worked, thanks, and thanks too for your comment about this tutori=
al, as
a comment for those who can be interesting in beginning learning windows,=
 I feel
it is a good way for preparing oneself to that kind of things, although I=
 thing
it is not explanative enough, it's too superficial. I would recommend eye=
 the
winprog tutorial (forger's) which explains the functions a bit more and t=
hen see
the reliable, while they (reliable) don't explain them a little more, tho=
ugh
reliable's tutorial can be enough for a starting.
Naturally, for true learning, buy a book, online tutorials are only for g=
et
started.
I agree you in that of know or not C before C++, you don't need c before =
c++,
but many people has a bad logical thought: they don't notice that after C=
 is
easier learn C++ than learn C++ directly simply because the half is the s=
ame, if
you learn first C and then C++, when you're studying C++ you know yet the=
 half
or more of what you're reading, but if you want only C++ and not need C, =
why
have to learn one and a half programming language? Learn just one, the on=
e you
need.
At the same way we could say, if you want learn C, learn first C++, it's =
the
same case, when you study C after C++ you know yet more than a half of it=
, it's
more, C++ has more of C than C of C++, so it is faster the inverse way:

Demonstration:
Time for learning C alone: say four months.
Time for learning C++ alone: Say five months (admit a little of confusion=
 is due
to this difference in time of learning directly).
Proportion of C++ inside C: 50%
Proportion of C inside C++: 75%
What to do from C to C++: change and add names and add capabilities.
What to do from C++ to C++: change names and don't use some capabilities.
First C and second C++:
4 moths learnig C + 5 * 0.50 (100 - 50%/100) =3D 4 + 2.5 =3D 6.5 months, =
add 0.5
months for "take the feeling to object oriented programming"           ^|=
 This
is what remains unknown.                Total: 7 months.
First C++ and second C:
5 months learning C++ + 4 * 0.25 (100 - 75%/100) =3D 5 + 1 =3D 6 months. =
You don't
need add anything because the object oriented things are not needed, you =
simply
don't use them.
Result: C++ -> C is one month faster than C -> C++. And the calculus has =
been
made to favour C->C++.

Of course, and that is another thing, know both is better than only one, =
so you
have at your disposal some functions that perhaps in some moments could m=
ake
some things easier, but I think those would be rare, and there is nothing=
 you
can't do with c++ but can with c, however there are things you can do wit=
h C++
you cannot with C (object orienting), but you can simulate object orienti=
ng with
structs (I am not speaking about the effectivity of this), but how can yo=
u
simulate objects if you don't know them?.

Napoleon Ahiable escribi=F3:

> Hi there,
>
> There solution to your problem can be found at http://www.relisoft.com/=
forum
> check Windows API Programming in C++. Below is an excerpt of the discus=
sions
> that went on.
>
> ..... The hInstance member of _class is a HANDLE (that is, _class is a
> WNDCLASSEX, and WNDCLASSEX's 'hInstance' member is a HANDLE, not, as on=
e
> might guess from it's name, an HINSTANCE).  mingw does define HANDLE as=
 a
> pointer to void.  But LoadImage is looking for an honest-to-god HINSTAN=
CE.
>
> There is also a solution on the forumwhich works fine on Dev-C++.
>
> Napoleon.
> ----- Original Message -----
> From: "Carlos Garc=EDa del Monte" <cg...@wo...>
> To: "dev-cpp-users-list" <dev...@li...>
> Sent: Saturday, July 06, 2002 11:58 AM
> Subject: Re: [Dev-C++] conversion from void *(and is neither void nor
> pointer)
>
> > Thanks, it works in some sites, but now I have found a place where it=
 is a
> 0
> > in LoadImage, and it still says that, the parameter expected is an UI=
NT, I
> do
> > everything but no way!
> >
> > Here is the line:
> >     _class.hIcon =3D reinterpret_cast<HICON> (
> >         ::LoadImage (_class.hInstance,
> >     MAKEINTRESOURCE (resId),
> >     IMAGE_ICON,
> >     ::GetSystemMetrics (SM_CXICON),
> >     ::GetSystemMetrics (SM_CYICON),
> >     0));
> >
> > I changed the first with  _class.hIcon =3D ::LoadIcon(_class.hInstanc=
e,
> > MAKEINTRESOURCE(resId)); and it says the same error. The same if I pu=
t 1-1
> > instead of 0, or if I declare a UINT var =3D 0; and write var. I use =
the
> > LR_DEFAULTSIZE flag and still says that.
> > Here is the code of the full function where the two lines still have =
error
> > are:
> >
> > void WinClass::SetResIcons (int resId)
> > {
> > UINT zero =3D 0;
> >     _class.hIcon =3D reinterpret_cast<HICON> (
> >         ::LoadImage (
> >             _class.hInstance,
> >             MAKEINTRESOURCE (resId),
> >             IMAGE_ICON,
> >             ::GetSystemMetrics (SM_CXICON),
> >             ::GetSystemMetrics (SM_CYICON),
> >                0));
> >     // Small icon can be loaded from the same resource
> >     _class.hIconSm =3D reinterpret_cast<HICON> (
> >         ::LoadImage (
> >             _class.hInstance,
> >             MAKEINTRESOURCE (resId),
> >             IMAGE_ICON,
> >             ::GetSystemMetrics (SM_CXSMICON),
> >             ::GetSystemMetrics (SM_CYSMICON),
> >             0));
> > }
> >
> > Borland 5.5 compiles fine, but I prefer Dev, it's more comfortable ID=
E
> than
> > those I found for Borland, with difference.
> >
> > P.S.: Some times the error has lines where the error is unreadable
> characters.
> >
> >
> >
> > -------------------------------------------------------
> > This sf.net email is sponsored by:ThinkGeek
> > Got root? We do.
> > http://thinkgeek.com/sf
> > _______________________________________________
> > Dev-cpp-users mailing list
> > Dev...@li...
> > https://lists.sourceforge.net/lists/listinfo/dev-cpp-users
> >
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.372 / Virus Database: 207 - Release Date: 20/06/02