C / C++ / MFC

CMenus : How to use menu handles instead of menu resource ID when needed ?

16-Sep-14 5:36

See the comments at http://msdn.microsoft.com/en-gb/library/windows/desktop/aa379913(v=vs.85).aspx[^].

sdancer7515-Sep-14 20:45

sdancer75

15-Sep-14 20:45

Hi,

I show that some CMenu methods, need the ID of the menu that is already created inside the resource manager.

But, if the CMenu is created dynamically how do I assign a unique ID for that object ? If that is not possible, then how can I "translate" the menu handle to this unique resource ID so it would compatible with the Win32 API functions ?

Regards,

sdancer75

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

Richard MacCutchan15-Sep-14 21:19

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

15-Sep-14 21:19

If it is a dynamically created menu then it cannot have a resource id, since there is no associated resource. It would probably help if you showed the piece of code that you are having a problem with.

CPallini15-Sep-14 21:22

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

15-Sep-14 21:22

You can definitely assign IDs to dynamically created menu items, see the CMenu::AppendMenu[^] method.

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sdancer7515-Sep-14 22:07

sdancer75

15-Sep-14 22:07

From MSDN

AppendMenu function

7 out of 10 rated this helpful - Rate this topic
Appends a new item to the end of the specified menu bar, drop-down menu, submenu, or shortcut menu. You can use this function to specify the content, appearance, and behavior of the menu item.

That's correct, but if the menu is a brand new dynamically created popupmenu and I dont want to append it to an existing menu, there is no point to use AppendMenu, right ?

sdancer75

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

CPallini15-Sep-14 23:04

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

15-Sep-14 23:04

Not right. When you dynamically create a menu, it has no items: you have to use the AppendMenu method to add, at least a menu item to it.

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Richard MacCutchan16-Sep-14 2:30

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

16-Sep-14 2:30

I suspect you are getting your terminology wrong, and as suggested please show the code that you are having problems with, and why you think it needs this id.

sdancer7516-Sep-14 21:35

sdancer75

16-Sep-14 21:35

Richard MacCutchan wrote:
I suspect you are getting your terminology wrong, and as suggested please show the code that you are having problems with, and why you think it needs this id.

Yes, there was a terminology wrong from my side..... The misunderstanding was done when I tried to initialize a CXTPBrowseButton from Codejock's framework and I needed a resource ID menu but I only create that menu dynamically.

The code example I tried to customize is :

C++

m_edit1.Initialize(this, BES_XTP_POPUPMENU, IDR_POPUP);

and is declared like

C++

virtual bool Initialize(CWnd* pParentWnd, DWORD dwBStyle, UINT nMenu = 0, int nSubMenuIndx = 0);

It seems that I dont have an option in this situation to pass an object handle !!!!

My worng thoughts was that I just needed an ID just to make an object unique for the internal use of the MFC framework but I didn't thought that it was merely a unique RESOURCE ID.

Thanks for clarifying this..... I just dazed and confused.

sdancer75

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

Richard MacCutchan16-Sep-14 21:57

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

16-Sep-14 21:57

I have never come across Codejock so cannot offer any suggestions.

Richard MacCutchan16-Sep-14 2:29

Re: CMenus : How to use menu handles instead of menu resource ID when needed ?

16-Sep-14 2:29

That's the id of the associated command, which is not the same as resource id. But maybe that is what the OP is really asking for.

CPallini16-Sep-14 2:45

Passing a class to a sprintf() and similar

16-Sep-14 2:45

You are right, of course (on both the points, I hope).

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Crazy Joe Devola14-Sep-14 19:45

Crazy Joe Devola

14-Sep-14 19:45

I am trying to pass a class I wrote to sprintf(). Not the class itself actually, but a pointer to a string the class holds.

With the VC++ CString class it works fine:
sprintf(t, "%s", cst);

But with my class, it either crashes the program or puts garbage into the t buffer:
sprintf(t, "%s", c);

Unless I use casting, and then it works ok:
sprintf(t, "%s", (char *)c);

What is my class missing? Some kind of an operator?
Here is my code:

C++

class C1
{
public:
C1()
{
sprintf(m_Data,"C1 class");
}

operator char *() { return m_Data; }

private:
char m_Data[100];
};

int main(int argc, char* argv[])
{
char t[1000]="";
C1 c;
CString cst("Test c string");

sprintf(t, "%s", cst);
sprintf(t, "%s", c);
return 0;
}

CPallini14-Sep-14 20:01

14-Sep-14 20:01

Crazy Joe Devola wrote:
What is my class missing? Some kind of an operator?

You are missing nothing: Try the following statement:

C++

char * p = c;

However the cast (either the one you used or the static_cast<char *>()) is required in sprintf due to its signature (the type of its variadic arguments is established dynamically based on the fmt parameter) the char*() operator must be explicitely called.

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Crazy Joe Devola14-Sep-14 20:07

Crazy Joe Devola

14-Sep-14 20:07

Thank you.
Yes, char * works.
However, when i use the CString class as in my example, no casting or conversion is required at all. What does the CString class have that my C1 does not? (obviously a lot Smile | :)

but specifically for what I am trying to do...)

CPallini15-Sep-14 2:15

15-Sep-14 2:15

You are right, of course. And that is, at the moment, a mystery to me too. Smile | :)

However, have a look at this MSDN page: CString::operator LPCTSTR[^].
That's make me guess in your actual code m_Data is not the unique (and not the first) data member.

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Richard MacCutchan16-Sep-14 2:59

16-Sep-14 2:59

I just tested OP's code (without the CString - no MFC or ATL) and it sends the actual C1 object as the last parameter, so the pointer will be rubbish. I also would like to know how CString manages to coerce the () operator without a cast.

CPallini16-Sep-14 3:11

16-Sep-14 3:11

It is not rubbish, in my test (VS2012). It is pointer to the C1 object, having the same address of its first data member (m_Data) in this simple case, so everything goes right (of course if you insert, before m_Data, another member variable, for instance an int, the sprintf gets some garbage).

In the linked MSDN page they indded suggest to explicitely cast the CString object when used as sprintf parameter.

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Richard MacCutchan16-Sep-14 3:40

16-Sep-14 3:40

Interesting. I used VS2010 Express, and copying OP's code, it copies the entire object onto the stack, thus the 'pointer' is garbage. When I use a cast it pushes the address of the object onto the stack and works as it should. More testing required ...

Richard MacCutchan16-Sep-14 4:04

16-Sep-14 4:04

See my answer to OP below.

Bram van Kampen16-Sep-14 16:45

Bram van Kampen

16-Sep-14 16:45

Well I have noticed,

VC 2012 has different parsing and scanning rules than earlier versions. The question is: Did the rules change in the standard, or was it incorrectly implemented by Microsoft.

Smile | :)

Bram van Kampen

Richard MacCutchan16-Sep-14 4:04

16-Sep-14 4:04

OK, I finally figured it out. CString is a bit more of a sophisticated class, and will not use a fixed length buffer for its data. It uses a dynamically allocated one, and as long as that is the first data item in the class definition, the sprintf call will work; although it is luck rather than anything else. You can check this out with the following code:

C++

class C1
{
public:
    C1()
    {
        // allocate space for the text and then copy to the dynamic buffer
        m_Data = (char*)malloc(100);
        sprintf(m_Data,"C1 class");
    }
    
    operator char *() { return m_Data; }
    
private:
    char* m_Data; // make buffer a pointer
    
    };

When you now use the object without the cast, it just copies the object's data onto the stack, and since this data is a pointer to the actual text it all works as you expect. But be aware that this may have unintended consequences, so always use the cast when you want this behaviour.

CPallini16-Sep-14 4:33

16-Sep-14 4:33

However, I don't see the difference on my system (that is it works with m_Data as provided in the OP).

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Richard MacCutchan16-Sep-14 5:03

16-Sep-14 5:03

Definitely different for me, it only worked with the modified code.

CPallini16-Sep-14 5:13

16-Sep-14 5:13

And apparently the 'strange case' is mine.

THESE PEOPLE REALLY BOTHER ME!! How can they know what you should do without knowing what you want done?!?!
-- C++ FQA Lite

Richard MacCutchan16-Sep-14 5:30