C / C++ / MFC

6-Jul-06 22:50

I am writing a C++ class. In the constructor I create a WNDCLASSEX WndClsEx structure. I want to pass a method of the class as a parameter to the WndClsEx.lpfnWndProc function (WndClsEx.lpfnWndProc = MyWindowProc;). The compiler gives me an error. Do you know how I can solve the problem?

Thank you!

modified 9-Mar-17 17:18pm.

Naveen6-Jul-06 23:05

Naveen

6-Jul-06 23:05

whats the error?

nave

Daniel Kanev6-Jul-06 23:24

6-Jul-06 23:24

The error I get is:

error C2440: '=' : cannot convert from 'long (__stdcall CDrawingControl::*)(struct HWND__ *,unsigned int,unsigned int,long)' to 'long (__stdcall *)(struct HWND__ *,unsigned int,unsigned int,long)'

Thank you!

modified 9-Mar-17 17:17pm.

Naveen6-Jul-06 23:26

Naveen

6-Jul-06 23:26

how did u declared the "MyWindowProc" funtion?

nave

ThatsAlok7-Jul-06 0:33

ThatsAlok

7-Jul-06 0:33

Daniel Kanev wrote:

error C2440: '=' : cannot convert from 'long (__stdcall CDrawingControl::*)(struct HWND__ *,unsigned int,unsigned int,long)' to 'long (__stdcall *)(struct HWND__ *,unsigned int,unsigned int,long)'

add STATIC in front of that function!

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Daniel Kanev7-Jul-06 1:07

7-Jul-06 1:07

It works fine, thanks!

modified 9-Mar-17 17:16pm.

Justin Tay6-Jul-06 23:14

Justin Tay

6-Jul-06 23:14

Is the method in the class (MyWindowProc) a static method? If not you have a mismatched calling convention.

Daniel Kanev7-Jul-06 1:06

7-Jul-06 1:06

It works, thank you!

modified 9-Mar-17 17:17pm.

still about modeless dialog

David Crow7-Jul-06 3:23

David Crow

7-Jul-06 3:23

See here.

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Class communication

HakunaMatada6-Jul-06 22:41

HakunaMatada

6-Jul-06 22:41

How do I set up a two way communication between two classes?

Lets say I have Class A and Class B. Now, Class A must be able to call functions of Class B and Class B must be able to call functions of Class A.

Is it possible?

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Re: Class communication

ThatsAlok6-Jul-06 22:57

ThatsAlok

6-Jul-06 22:57

Hakuna-Matada wrote:
ets say I have Class A and Class B. Now, Class A must be able to call functions of Class B and Class B must be able to call functions of Class A.

FORWARD Decalartion is the key to your Question!
eg
class a;
class b{
public:
a aObj;
};

class a
{
public:
b bObj;
};

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You

Re: Class communication

Steve Echols6-Jul-06 23:05

Steve Echols

6-Jul-06 23:05

Yes it's possible, but you'll have to seperate declaration from implementation:

In .h:

<br />
class A;<br />
class B;<br />
<br />
class A<br />
{<br />
public:<br />
    B* m_pB;<br />
<br />
    void callB();<br />
    void doSomething();<br />
};<br />
<br />
class B<br />
{<br />
public:<br />
    A* m_pA;<br />
<br />
    void callA();<br />
    void doSomething();<br />
};<br />

In .cpp:

void A::callB()<br />
{<br />
    m_pB->doSomthing();<br />
}<br />
<br />
void A::doSomething()<br />
{<br />
    // do whatever to A<br />
}<br />
<br />
void B::callA()<br />
{<br />
    m_pA->doSomthing();<br />
}<br />
<br />
void B::doSomething()<br />
{<br />
    // do whatever to B<br />
}<br />

Usage:

A a;<br />
B b;<br />
<br />
a.m_pB = &b;<br />
b.m_pA = &a;<br />
<br />
a.callB();<br />
b.callA();<br />

Pretty generic, hope that helps.

- S
50 cups of coffee and you know it's on!

Re: Class communication

David Crow7-Jul-06 3:27

David Crow

7-Jul-06 3:27

Hakuna-Matada wrote:
Is it possible?

In addition to Steve's suggestion, the methods that you wish to invoke could be made static. That way, a class does not have to contain an instance of the other.

class A
{
public:
    static fooA();
};
 
class B
{
public:
    static fooB();
};

Now in class A's methods, you can call B::fooB(), and in class B's methods, you can call A::fooA().

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Finding duplicates

RChin6-Jul-06 22:34

RChin

6-Jul-06 22:34

Hey guys.
What do you recommend as the quickest method of finding duplicate values in a list of items or array.

These item type could be numeric or (in this case) a string.

In the past I've used the technique of inserting the items in an stl set. This would immediately flag if you are trying to insert the same item again. But this can get slow if I have a large list of items to wade through.

Are there any other techniques that you guys are using?

I Dream of Absolute Zero

Re: Finding duplicates

Steve Echols6-Jul-06 22:53

Steve Echols

6-Jul-06 22:53

If your list is sorted, you could use a binary search http://en.wikipedia.org/wiki/Binary_search[^].

If not sorted, you'll have to scan the entire list/array for duplicates. Re-creating your list, just to determine if there are duplicates, would not be the most efficient way to do it - just run a loop over the original list/array.

- S
50 cups of coffee and you know it's on!

Re: Finding duplicates

RChin7-Jul-06 9:02

RChin

7-Jul-06 9:02

Thanks. I'll do a quick sample test project to check the speed between the two methods.
The std::set insertion technique works fine (just finished the coding), but I suspect that it is not the fastest way of doing this.

I Dream of Absolute Zero

Desmo166-Jul-06 22:25

Desmo16

6-Jul-06 22:25

Hi all,

I crated a new dialog called IDD_RIPORTO.
I also added a class called riporto.

If i do:

riporto temp;
temp.DoModal();

everything is ok, but if i do:

riporto* temp = new riporto();
temp->Create(IDD_RIPORTO,this);

the application runs but crashes at runtime
when the above code is executed.

If i do:

CDialog *temp = new CDialog();
temp->Create(IDD_RIPORTO,this);

everything goes well but of course
i have no access to riporto data members,
so i think this isn't the correct way.

Where i go wrong ?

Thank you so much,
Deamo16.

Sarath C6-Jul-06 22:34

Sarath C

6-Jul-06 22:34

Desmo16 wrote:
riporto* temp = new riporto();
temp->Create(IDD_RIPORTO,this);

Read the article in MSDN regarding modeless dialog.
It clearly say that, you need customized contructor to create that dialog.
the default constructor of you dialog class calls CDialog(IDD); to initialize the dialog with template.

Desmo16 wrote:
temp->Create(IDD_RIPORTO,this);

you are trying to create on already created object. So it wont work.
define you own contructor to create modeless dialog. never allow contructor to create dialog with template if you are looking for a modeless dialog.

SaRath.

"Where I am from, there is no plan B. So, take advantage of today becuase tomorrow is not promised. - 50 Cent"

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Hamid_RT6-Jul-06 23:08

Hamid_RT

6-Jul-06 23:08

when you run Domodal() is ok but when you use create you get error or no?

whitesky

Desmo166-Jul-06 23:40

Desmo16

6-Jul-06 23:40

when i use create i get error at runtime.
I'd like to understand how to write my own
constructor as i was told to do in the previous post
or if there's a sample coda somewhere.

Hamid_RT6-Jul-06 23:52

Hamid_RT

6-Jul-06 23:52

You using

riporto* temp = new riporto();<br />
temp->Create(IDD_RIPORTO,this);

and you get error
and if you use this way you get error or no and answer to me,please

<br />
riporto* temp = new riporto(this);<br />
riporto::riporto(CWnd* pParent /*=NULL*/)<br />
	: CDialog(CTest2::IDD, pParent)<br />
{<br />
BOOL o=Create(IDD,Parent);//if return 1 that not problem <br />
}<br />

whitesky