C / C++ / MFC

Re: Pocket PC windows and the Return Key, it always closes them :'(

31-Dec-07 5:00

Hi,
I'm starting to programm apps for PPC 2003 using VS 2005 and I have a strange problem, when I have a normal empty window and i press the return key the window closes as it I head used the close button.
Why is it so and how can i solve this ina clean and decent way?
btw: how can I change the close OK button to the normal one with the X?

Happy New Year
Owen

C^hris L^osinger31-Dec-07 9:08

C^hris L^osinger

31-Dec-07 9:08

see this[^] or this[^]

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Re: Pocket PC windows and the Return Key, it always closes them :'(

OwenBurnett31-Dec-07 10:16

Re: Pocket PC windows and the Return Key, it always closes them :'(

31-Dec-07 10:16

The links you'v posted does not apply to my problem, because thay are for normal windows APP's but I have a Pocket PC app, there are no default buttons created.
The secund link points to a possible solution, but i think there must be a one special for PPC's that may fit much better

C^hris L^osinger31-Dec-07 10:23

C^hris L^osinger

31-Dec-07 10:23

they will both work.

did you even try them ?

here's another example[^]

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Re: Pocket PC windows and the Return Key, it always closes them :'(

OwenBurnett31-Dec-07 10:44

Re: Pocket PC windows and the Return Key, it always closes them :'(

31-Dec-07 10:44

I already figured out a similar workaround using OnCommand, but I have than the problem that than also the Enter Key does not work any ware, when I intercept the return key in OnCommand it is not passed to OnChar, or else, i assume PreTranslateMessage will have the same problems.
The only thing bypasses the interception is OnKeyUp, OnKeyDown seems to dont work at all on PPC 2003 for the enter key.

I'm looking for a realy clean solution.

C^hris L^osinger31-Dec-07 10:51

C^hris L^osinger

31-Dec-07 10:51

OwenBurnett wrote:
i assume PreTranslateMessage will have the same problems.

try it

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Re: Pocket PC windows and the Return Key, it always closes them :'(

OwenBurnett31-Dec-07 12:41

Simple C++ Inheritance and Performance

31-Dec-07 12:41

Seems to work better than OnCommand,
OnKeyDown is triggerd properly but with nChar == 0, but this is a minor problem and can be easly handled.
thx.

OnMouseMove Flags

Hakan Bulut31-Dec-07 4:31

Hakan Bulut

31-Dec-07 4:31

From where i can look at the OnMouseMove Flags for the some mousemove events.

Bitte tun Sie mir nicht antworten, wenn Sie nicht wissen, die Ursache des Problems wirklich oder nur als Antwort. Was ist das? Dies ist das Buch sitzen.

Re: OnMouseMove Flags

ashukasama31-Dec-07 4:42

ashukasama

31-Dec-07 4:42

nFlags
Indicates whether various virtual keys are down. This parameter can be any combination of the following values:

MK_CONTROL Set if the CTRL key is down.

MK_LBUTTON Set if the left mouse button is down.

MK_MBUTTON Set if the middle mouse button is down.

MK_RBUTTON Set if the right mouse button is down.

MK_SHIFT Set if the SHIFT key is down.

Re: OnMouseMove Flags

Hakan Bulut31-Dec-07 7:38

Hakan Bulut

31-Dec-07 7:38

Thanks

Bitte tun Sie mir nicht antworten, wenn Sie nicht wissen, die Ursache des Problems wirklich oder nur als Antwort. Was ist das? Dies ist das Buch sitzen.

Lea Hayes31-Dec-07 2:50

Lea Hayes

31-Dec-07 2:50

Hi,

I am working on an element of a program which is performance cruical and I wanted to clarify something with regards to basic C++ inheritance.

Consider the following:

class BaseClass<br />
{<br />
public:<br />
   BaseClass();<br />
<br />
   void foo();<br />
<br />
private:<br />
   int baz;<br />
};<br />
<br />
class AnotherClass : public BaseClass<br />
{<br />
public:<br />
   AnotherClass();<br />
<br />
   void bar();<br />
};

It is important to note that no virtual functions will be used within this element; including no virtual destructor.

My question is this, would there be any performance differences between the above source and the source listed below?

class CombinedClass<br />
{<br />
public:<br />
   CombinedClass();<br />
<br />
   void foo();<br />
   void bar();<br />
<br />
private:<br />
   int baz;<br />
};

The first example would be easier for me to maintain because there will be many variations of 'AnotherClass'. Does anybody know of the nitty-gritty low-level differences between the two and any such differences in performance?

Also do overloaded methods cause performance differences?

Any advice would be greatly appreciated!
Lea Hayes

Florin Crişan31-Dec-07 3:14

31-Dec-07 3:14

Theoretically there should be no performance difference. The calls to foo() and bar() should be non-virtual in either case. But you can try having a look at the generated assembler code just to be sure.

BTW, if it's not a secret, what are you doing so special that you cannot use a virtual function call?

Florin Crisan

Florin Crişan31-Dec-07 3:17

31-Dec-07 3:17

On second thought (assuming your constructors are not trivial and cannot be optimized away), if you use two classes you would get two function calls: first to the constructor of the derived class, then to the constructor of the base class. But the other function calls should be the same.

Florin Crisan

Lea Hayes31-Dec-07 4:23

Lea Hayes

31-Dec-07 4:23

Hi,

It is a math class which will be used extremely frequently. There are a variety of different math classes, and some of which are derived upon the others...There is no multi-inheritance, and I have ruled out virtual methods here because they would offer no gain, and automatically require additional memory to reference a vtable.

Thanks for your advice!

Re: Simple C++ Inheritance and Performance [modified]

CPallini31-Dec-07 3:25

CPallini

31-Dec-07 3:25

lhayes00 wrote:
My question is this, would there be any performance differences between the above source and the source listed below?

IMHO none noticeable (There are two constructors instead of one, though, if you have a huge number of objects...).

lhayes00 wrote:
The first example would be easier for me to maintain because there will be many variations of 'AnotherClass'.

The above is a good reason to go on with inheritance.

lhayes00 wrote:
Also do overloaded methods cause performance differences?

IMHO no, they are translated by the compiler to different named methods (in fact functions).

BTW C++ language is fairly efficient (is one of its design goals), I think that you should first address your efforts to good, clean design and then on optimization of your algorithms, and finally worry about efficiency of different language constructs.

Please note that I gave you general guidelines, I'm not an expert of that

lhayes00 wrote:
nitty-gritty low-level

things.

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Florin Crişan31-Dec-07 3:28

What other people say about this:

31-Dec-07 3:28

I should learn to read the whole message Blush | :O

Also do overloaded methods cause performance differences?

Well, a normal non-virtual function call has the normal overhead of a, well, normal function call. That is, the arguments are pushed to the stack, the return address is pushed to the stack, etc.

(As far as I know) If you have a polymorphic object, in most implementations it keeps a (hidden) pointer to a table of function pointers (known as 'vtable'). So, before making the call, the pointer to the vtable and then the one to the function would have to be de-referenced. (I really don't know how expensive that is; it may be significant on some systems, but probably nothing significant for normal use).

However, if the compiler is able to tell the exact type of the object, it won't need to call the function virtually.

For example

<br />
Derived x;<br />
x.bar(); // x is a derived -- call Derived::bar() directly<br />
<br />
Base *x;<br />
x->foo(); // is x a Base or a Derived? use the function pointer to be sure<br />

If you really think it would make a difference, try it both with virtual and with non-virtual and see what happens. (And let us known what the result was Wink | ;-)

)

Florin Crisan

Florin Crişan31-Dec-07 3:35

31-Dec-07 3:35

Googling around for virtual function calls, I found this research paper[^], but I'm too lazy to read it. Hope it helps.

Florin Crisan

Happy New Year!

Florin Crişan31-Dec-07 3:40

31-Dec-07 3:40

What a mess. It took me so many messages to say so little. D'Oh! | :doh:

I'm going to get some sleep before the party. Happy New Year!

Florin Crisan

CPallini31-Dec-07 3:42

CPallini

31-Dec-07 3:42

Florin Crisan wrote:
Also do overloaded methods cause performance differences?

Florin Crisan wrote:
(As far as I know) If you have a polymorphic object, in most implementations it keeps a (hidden) pointer to a table of function pointers (known as 'vtable'). So, before making the call, the pointer to the vtable and then the one to the function would have to be de-referenced. (I really don't know how expensive that is; it may be significant on some systems, but probably nothing significant for normal use).

However, if the compiler is able to tell the exact type of the object, it won't need to call the function virtually.

For example

Derived x;
x.bar(); // x is a derived -- call Derived::bar() directly

Base *x;
x->foo(); // is x a Base or a Derived? use the function pointer to be sure

Method overload and method override are two quite distinct concepts, he asked for the former, you're talking about the latter.

Florin Crisan wrote:
Derived x;
x.bar(); // x is a derived -- call Derived::bar() directly

Base *x;
x->foo(); // is x a Base or a Derived? use the function pointer to be sure

AFAIK method invocation is always done via vtables.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Florin Crişan31-Dec-07 3:46

31-Dec-07 3:46

CPallini wrote:
Method overload and method override are two quite distinct concepts, he asked for the former, you're talking about the latter.

My bad.

CPallini wrote:
AFAIK method invocation is always done via vtables.

I remember reading differently in Stroustrup's book, but it might be just the lack of sleep. I guess it's really up to the compiler's implementer.

Florin Crisan

CPallini31-Dec-07 4:09

CPallini

31-Dec-07 4:09

Florin Crisan wrote:
I remember reading differently in Stroustrup's book

Well, I surely don't debate against C++ founder, maybe you're right.

Happy New Year
Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]