CheckMenuItem doesn`t check menu item!!!

[Cesario Simões]

I`m trying check/uncheck a menu item (in the pop-up, of course) but it doesn`t work!
I`m using this code:
void CAgendaDlg::OnMenuItemToCheckOrUncheck()
{
UINT nMenuState;

nMenuState = m_menuPrincipal->GetMenuState( ID_LEMBRARSENHACONTA, FALSE );
if ( nMenuState == 0xFFFFFFFF )
{//erro: não tem este item:
AfxMessageBox ( "Não tem este item no menu.",MB_OK );
}
else
{
if (nMenuState && MF_CHECKED )//MF_CHECKED==8
{
//nMenuState = m_menuPrincipal->CheckMenuItem( ID_LEMBRARSENHACONTA, MF_CHECKED );
//nMenuState = m_menuPrincipal->CheckMenuItem( 5, MF_BYPOSITION | MF_CHECKED );
nMenuState = CheckMenuItem( ID_LEMBRARSENHACONTA, MF_CHECKED );
}
else
{
nMenuState = m_menuPrincipal->CheckMenuItem( ID_LEMBRARSENHACONTA, MF_UNCHECKED );
//nMenuState = m_menuPrincipal->CheckMenuItem( 5, MF_BYPOSITION | MF_UNCHECKED );
nMenuState = CheckMenuItem( ID_LEMBRARSENHACONTA, MF_UNCHECKED );
}
if ( nMenuState == 0xFFFFFFFF )
{//erro: não tem este item:
AfxMessageBox ( "Não tem este item no menu (2).",MB_OK );
}
UpdateData(FALSE);
}
}
Please, help me!

Cesario Simões, Jr.

[Cesario Simões]

I`m using a dialog with menu... This function work in it?

I`m creating the menu using:

m_menuPrincipal = new CMenu;
m_menuPrincipal->LoadMenu(IDR_MENU2);//SetMenu
SetMenu ( m_menuPrincipal );

I have tryed other method: Overriding the message:
void CAgendaDlg::OnUpdateLembrarsenhaconta(CCmdUI* pCmdUI)
{
UINT nMenuState;

nMenuState = m_menuPrincipal->GetMenuState( ID_LEMBRARSENHACONTA, FALSE );
if ( nMenuState == 0xFFFFFFFF )
{//erro: não tem este item:
AfxMessageBox ( "Não tem este item no menu.",MB_OK );
}
else
{
if (nMenuState && MF_CHECKED )//MF_CHECKED==8
{
pCmdUI->SetCheck( 0 );
}
else
{
pCmdUI->SetCheck( 1 );
}
}
}

But it doesn`t work too!


Cesario Simões, Jr.

[Coder]

It looks like an error in your code.

if (nMenuState && MF_CHECKED )//MF_CHECKED==8

This will always be true if nMenuState is not 0. I think you meant:
if( 0 != (nMenuState & MF_CHECKED) ) {
//etc.



The single ampersand performs a bitwise AND, the '&&' is a logical AND.

[Cesario Simões]

I want exactly a logical AND: If it`s TRUE the bit, I want to check the pop-up menu item. But I have another information: My application is dialog-based: it`s a dialog with menu... The function "CheckMenuItem" works in a dialog menu?

Cesario Simões, Jr.

[Dave Lorde]

> I want exactly a logical AND: If it`s TRUE the bit

I think you'll find Coder is right. If you want to test whether the MF_CHECKED bit is set in nMenuState, you should use *bitwise* AND (&) not logical AND (&&).

The logical AND expression will be true if both arguments are non-zero, and nMenuState can be non-zero even if the MF_CHECKED bit is not set. The bitwise AND (&) tests that at least one corresponding bit is set in both arguments, which is what you said you wanted.

Dave

[Cesario Simões]

OK! Isn`t the question... I have changed the code (changing from "&&" to "&") but it`s still not working properly! The pop-up menu item remains unchecked...

Related with the "&&" and "&" stuff:
I wrote this little piece of code and, testing and debuging, the results are:
UINT nMenuState, nTeste1 = 0, nTeste2 = 2, nTeste3 = 3;
BOOL bResult;
bResult = (nTeste1 & nTeste2 );//0&2=0 00000000b & 00000010b = 0
bResult = (nTeste1 && nTeste2 );//0&&2=0 00000000b && 00000010b = 0
bResult = (nTeste2 & nTeste3 );//2&3=2 00000010b & 00000011b = 00000010b
bResult = (nTeste2 && nTeste3 );//2&&3=1(TRUE)00000010b && 00000011b = 00000001b
bResult = (nTeste1 & nTeste2 );//0&2=0 00000000b & 00000010b = 00000000b
bResult = (nTeste1 && nTeste2 );//0&&2=0 00000000b && 00000010b = 00000000b
( BOOL is realy an int )

Doubt? Try it!
:-)

Cesario Simões, Jr.

[Dave Lorde]

What's so surprising? The results are just what I would expect from those operators. It's pretty basic stuff.

To rephrase what I said before: '&&' returns true if both arguments are true (non-zero), and false otherwise. '&' returns the bits set that are common to both arguments.

Dave

[Jason Teagle]

Regarding the '&' vs. '&&' - your results are, of course, correct; but you are getting confused by them.

If you have a value, x, which may or may not have one or more bits set in it, and you want to find out if it has the MF_CHECKED attribute, the correct, FULL test is:

if ( (x & MF_CHECKED) == MF_CHECKED)...

This performs a bitwise comparison, and returns the set of bits which are non-zero in both values (i.e., it masks out all the bits we are not interested in, and leaves the rest). Because we want to see if MF_CHECKED is present, we must compare the result with MF_CHECKED to make sure those bits were present. Thus, if MF_CHECKED was 9 (1001b):

(2 & MF_CHECKED == MF_CHECKED) is FALSE, since 2 (0010b) does NOT contain both the bits in MF_CHECKED.

(13 & MF_CHECKED == MF_CHECKED) is TRUE, since 13 (1101b) contains both the bits in MF_CHECKED.

If the value you want to compare with (MF_CHECKED in this case) only contains one non-zero bit (which is the whole point of mutually-exclusive masks), then the test can be shortened to

if (x & MF_CHECKED)...

since the result of the bitwise comparison will be either equivalent to MF_CHECKED if the one bit is present, or 0.

What this is really saying is

if ( (x & MF_CHECKED) != FALSE)... (FALSE = 0)

What the following is saying:

if (x && MF_CHECKED)...

is equivalent to

if (x != FALSE && MF_CHECKED != FALSE)...

Summary: '&&' and '||' should ONLY be used to create an 'if' when you want two or more conditions to cause the 'if' code to be executed ('if (my_hair_is_green AND my_eyes_are_blue)' ). If you want to perform a test to see if a value includes a mask, use '&'.

Although your results seem to show that you are right, I'm afraid it's just a coincidence.

[Cesario Simões]

OK, you all are correct and I give thanks: your explanation avoid all doubts related with operators '&' and '&&'. But the original question remains unsolved: 'Why the pop menu item isn`t checked?'

Cesario Simões, Jr.

[cooper_nc]

I have the same problem also. I made a new menu item, but for some reason
I can't figure out how to tell it to check and uncheck itself.

Ernie

[Jason Teagle]

Now that I have looked at your code, I can see the problem. Consider the menu:

m_pMenu --> Popup 1 Popup 2 Popup 3
Item 1-1 Item 2-1 Item 3-1
Item 1-2 Item 2-2 Item 3-2
Item 1-3 Item 3-3
Separator
Item 1-4






What you appear to be attempting to do is to check, for example, the Item 1-4 item. What you must remember is that in the above example, m_pMenu points to a menu which contains three items: Popup 1, Popup 2 and Popup 3. As far as m_pMenu is concerned, there is nothing else in its menu. Therefore, attempting to check position 4 or ID_MNU_ITEM_1_4 on m_pMenu has no effect - because m_pMenu does not contain that index or command ID.

Item 1-4 is actually in Popup 1's menu, which is a submenu (but as far as the system is concerned, a menu in its own right). THAT menu DOES have a position 4 and the above ID.

Therefore, you must call m_pMenu->GetSubMenu(0) to retrieve a pointer to Popup 1's menu (position index 0), and THEN check the menu item from there.

Does this help?

[cooper_nc]

I am having the exact problem... I can get the program to tell me whether the
menu is checked or unchecked, but I cannot get it to change it. There has to be a real simple solution... but in hours I cannot find it.

Here is my current code... maybe I am using the wrong function.

Thanks... and if I figure it out... I'll let you all know.

Ernie


void CMainFrame::OnOptionsDisplaymaintitle()
{
CMenu m1;
CMenu *m2;
CString s;
UINT menuState;
UINT x;

m1.LoadMenu(IDR_MAINFRAME);

m2 = m1.GetSubMenu(4);

menuState = m2->GetMenuState(ID_OPTIONS_DISPLAYMAINTITLE,MF_BYCOMMAND);

x=m2->GetMenuItemID(0);
s.Format("%d=%d Mstate=%d (%d %d)",x, ID_OPTIONS_DISPLAYMAINTITLE,
menuState, MF_CHECKED, MF_UNCHECKED);
//OUTPUT IS 32775=32775 Mstate=8 (8 0)
AfxMessageBox(s);

if (menuState == 0xFFFFFFFF){
AfxMessageBox("menu help!");
}

if (0 != (menuState & MF_CHECKED) )
{
AfxMessageBox("CHECKED");
x=m2->CheckMenuItem(0,MF_BYPOSITION);
}
else if (0 == menuState)
{
AfxMessageBox("UNCHECKED");
x=m2->CheckMenuItem(0,MF_BYPOSITION);
}
}

[cooper_nc]

I was looking on this forum at other posts about menu's and one spawned me to finally figure it out. Here is the code that I now have that does actually work!


void CMainFrame::OnOptionsDisplaymaintitle()
{
CMenu *pAddinMenu, *pTopMenu;
UINT menuState;

pTopMenu = AfxGetMainWnd()->GetMenu();
pAddinMenu = pTopMenu->GetSubMenu(4);

ASSERT(pAddinMenu != NULL);

menuState = pAddinMenu->GetMenuState(ID_OPTIONS_DISPLAYMAINTITLE,MF_BYCOMMAND);

if (menuState == 0xFFFFFFFF){
AfxMessageBox("menu help!");
}
if (0 != (menuState & MF_CHECKED) )
{
pAddinMenu->CheckMenuItem(ID_OPTIONS_DISPLAYMAINTITLE,MF_UNCHECKED);
}
else if (0 == menuState)
{
pAddinMenu->CheckMenuItem(ID_OPTIONS_DISPLAYMAINTITLE,MF_CHECKED);
}
}

[Jason Teagle]

When you are calling CheckMenuItem(), you are not ORing in the MF_CHECKED bit in the section:

else if (0 == menuState)
{
AfxMessageBox("UNCHECKED");
x=m2->CheckMenuItem(0,MF_BYPOSITION);
}

You must use MF_BYPOSITION|MF_CHECKED to get the check mark in there. Also, it is not advisable to mix using MF_BYCOMMAND and MF_BYPOSITION - stick to one or the other.

Apart from that, everything looks OK.

[Cesario Simões]

It`s curious: When I check the menu item manualy (via resource editor) and I watch the answer of nMenuState = m_menuPrincipal->GetMenuState( ID_OPES_LEMBRARSENHACONTA, FALSE ); I can see the correct answer! The item is checked (nMenuState is 8). And when this item is manualy unchecked again, I can see nMenuState = 0...
But implementing your sugestion, the result is the same. And the item in menu always stay unchecked...

Cesario Simões, Jr.