Data does not show up in the combobox .

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hi all ,

I am trying to populate some data into the combobox control but when I run the program I do not see any data in it .
Here is the snippet :

C++

HWND hcombo  = CreateWindow(TEXT("COMBOBOX"), NULL, WS_VISIBLE | WS_CHILD  | WS_TABSTOP|CBS_DROPDOWNLIST|CBS_HASSTRINGS, 24, 8, 137, 25, hWnd, (HMENU) 1, NULL, NULL);

SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM) TEXT("Item1"));
SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM) TEXT("Item2"));
SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM) TEXT("Item3"));

Although if I set the cursel to some index as in SendMessage(hcombo, CB_SETCURSEL, 0, 0);
I do see the exact data in the combobox but the only data item rest do not populate in it .

I seek some help on it .
Many Thanks

Posted 23-Jan-15 21:09pm

iampradeepsharma

Updated 20-Apr-19 11:56am

Richard MacCutchan

v2

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Richard MacCutchan 24-Jan-15 5:07am

I just tried your code and it runs fine. You need to check with your debugger to see what is going on.

iampradeepsharma 24-Jan-15 11:07am

does it have to do with where the code was executed I mean I have put this code inside WM_CREATE inside switch case . Although I see on several other websites , they have placed it under WM_INITDIALOG . Although I tried to put it under it also but WM_INITDIALOG is never called . Do you have any insights on it .
Thanks Richard

Richard MacCutchan 24-Jan-15 11:30am

It depends on your application. If it is a normal Window app then WM_CREATE is probably a good place. If it is a dialog then WM_INITDIALOG should be OK.

It may be that there is something else in your code that is causing the problem, but without seeing some more it is impossible to say what that might be. As I suggested previously, you should use your debugger to capture a bit more information.

iampradeepsharma 24-Jan-15 11:59am

Do you actually see 3 items populated inside the combo box as with this code I tried on two machines but to no help .

Richard MacCutchan 24-Jan-15 12:03pm

As I said before, "it runs fine", meaning it works correctly. So you must be doing something else in your code that corrupts, or otherwise destroys, something in your ComboBox.

iampradeepsharma 24-Jan-15 12:34pm

Richard it would be a great help if you can share your file with me (if you don't mind) so that I can run directly on my machine .
thnx

Richard MacCutchan 24-Jan-15 13:45pm

There is nothing to share. I just pasted your code into a program after the window was created, and it worked.

iampradeepsharma 24-Jan-15 14:32pm

okay thnx

iampradeepsharma 25-Jan-15 5:59am

So the problem was in the size of the window 24, 8, 137, 25 , this 25 was the reason ..I made it to 100 and found out that it can show 3 items in it . Thanks Richard for putting some help to me .

Richard MacCutchan 25-Jan-15 7:03am

I guess I misunderstood your question. It only ever showed the items when I clicked to expand the dropdown.

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Michael Haephrati · Answer 1 · 2019-04-20T11:56:00

Based on this article[^], to make you code work, you need additional initialization as show in the example bellow:

int xpos = 100;            // Horizontal position of the window.
int ypos = 100;            // Vertical position of the window.
int nwidth = 200;          // Width of the window
int nheight = 200;         // Height of the window
HWND hwndParent = m_hwnd; // Handle to the parent window

HWND hWndComboBox = CreateWindow(WC_COMBOBOX, TEXT(""),
	CBS_DROPDOWN | CBS_HASSTRINGS | WS_CHILD | WS_OVERLAPPED | WS_VISIBLE,
	xpos, ypos, nwidth, nheight, hwndParent, NULL, HINST_THISCOMPONENT,
	NULL);

SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM)TEXT("Item1"));
SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM)TEXT("Item2"));
SendMessage(hcombo, CB_ADDSTRING, 0, (LPARAM)TEXT("Item3"));

// Send the CB_SETCURSEL message to display an initial item
//  in the selection field  
SendMessage(hWndComboBox, CB_SETCURSEL, (WPARAM)2, (LPARAM)0);