Thread: Get current selection from combobox

I cannot get the value of the item selected in a combobox.....
whats wrong? is it the integer number? should it be a pointer, an array?
I tried it all but non seems to work

Code:

switch (Message)
    { 
       case WM_COMMAND:
         {
	switch(LOWORD(wParam))
	{
                                           
	  case IDC_CON:
	  { 
                     number = SendMessage(hCombo,CB_GETCURSEL, 0,0); //Global variable
                    
                  }break;
                } 
        }break;
     }
//

Note: it is the first time I am using comboboxes and I have referrenced from MSDN

Compiler : DEV C++
OS: WIN XP

and so what is it returning?

If the return value is a valid index (ie not CB_ERR as previously mentioned by Niara) then it's -er- a valid index. Make sure you send the relevant control the CB_GETCURSEL message at an appropriate point in your program - just before you need to use it seems to be best. Test the return from SendMessage, though - use a message box to display the index; if nothing else it will provide you with some diagnostic regarding any problems at that point.

In short, given your description thus far, it seems to be an issue of program flow/execution order rather than an error(assuming you've made sure that the combobox handle used with SendMessage is valid?).

Code:

BOOL CALLBACK DlgNG(HWND dlgst, UINT Message, WPARAM wParam, LPARAM lParam)
{
HWND  hCombo;
TCHAR chTxt[3];    //text to add to combobox control(s) 
char *sel;    
	switch(Message)
	{
		case WM_INITDIALOG:
         //create a drop down combobox  
                 hCombo=CreateWindowEx(0,                                     //more or 'extended' styles
                              TEXT("COMBOBOX"),                      //'class' of control to create
                              NULL,                                  //the control caption
                              WS_CHILD|WS_VISIBLE|CBS_DROPDOWNLIST,      //control style: how it looks
                              190,                                    //control position: left
                              40,                                   //control position: top
                              50,                                   //control width
                              90,                                    //control height
                              dlgst,                                  //parent window handle
                              (HMENU)0x99,                                  //control's ID
                              g_hInst,                               //application instance
                              NULL); 
                              
                                  //add a string to the drop down combobox
        lstrcpy(chTxt,TEXT("2"));
        SendMessage(hCombo,CB_ADDSTRING,0,(LPARAM)chTxt); 
        lstrcpy(chTxt,TEXT("3"));
        SendMessage(hCombo,CB_ADDSTRING,1,(LPARAM)chTxt); 
        lstrcpy(chTxt,TEXT("4"));
        SendMessage(hCombo,CB_ADDSTRING,2,(LPARAM)chTxt);              
        	return TRUE;                      
                              
                              
	
		case WM_COMMAND:
			switch(LOWORD(wParam))
			{
				case ID_ST:
				sel=SendMessage(hCombo,CB_GETCURSEL,(WPARAM)0,(LPARAM)0);
				MessageBox(hwnd,sel,"start?",MB_OK);
				EndDialog(dlgst, ID_ST);
				break;
				case ID_CL:
					EndDialog(dlgst, ID_CL);
				break;
			}
		break;
		default:
			return FALSE;
	}
	return TRUE;
}

Here is the coding....actualy I have tried using a pointer to char and to int to get the return value...but got this warning

Objects.c: In function `DlgNG':
Objects.c:481: warning: assignment makes pointer from integer without a cast

....wats wrong?

You need to convert the numerical index to a string prior to using it in a message box:

Code:

TCHAR buffer[64];
wsprintf(buffer,_T("%d"),sel);
MessageBox(0,buffer,_T("start?"),MB_OK);

#include <tchar.h> after windows.h to use the _T macro or just use the TEXT macro instead.

edit: And declare 'sel' static (ie static int sel; )for proper scope.

edit2: biffed by Pronecracker.

On any selection made I get '0'
Whats happening?

Code:

BOOL CALLBACK DlgNG(HWND dlgst, UINT Message, WPARAM wParam, LPARAM lParam)
{
HWND  hCombo;
TCHAR chTxt[3];    //text to add to combobox control(s) 
TCHAR buffer[60];

static int sel;    
	switch(Message)
	{
		case WM_INITDIALOG:
         //create a drop down combobox  
                 hCombo=CreateWindowEx(0,                                     //more or 'extended' styles
                              TEXT("COMBOBOX"),                      //'class' of control to create
                              NULL,                                  //the control caption
                              WS_CHILD|WS_VISIBLE|CBS_DROPDOWNLIST,      //control style: how it looks
                              190,                                    //control position: left
                              40,                                   //control position: top
                              50,                                   //control width
                              90,                                    //control height
                              dlgst,                                  //parent window handle
                              (HMENU)0x99,                                  //control's ID
                              g_hInst,                               //application instance
                              NULL); 
                              
                                  //add a string to the drop down combobox
        lstrcpy(chTxt,TEXT("2"));
        SendMessage(hCombo,CB_ADDSTRING,0,(LPARAM)chTxt); 
        
        lstrcpy(chTxt,TEXT("3"));
        SendMessage(hCombo,CB_ADDSTRING,1,(LPARAM)chTxt); 
        
        lstrcpy(chTxt,TEXT("4"));
        SendMessage(hCombo,CB_ADDSTRING,2,(LPARAM)chTxt); 
                     
        	return TRUE;                      
                              
                              
	
		case WM_COMMAND:
			switch(LOWORD(wParam))
			{
				case ID_ST:
				sel=SendMessage(hCombo,CB_GETCURSEL,(WPARAM)0,(LPARAM)0);
				//MessageBox(hwnd,sel,"start?",MB_OK);
                wsprintf(buffer,TEXT("%d"),sel);
                MessageBox(dlgst,buffer,TEXT("start?"),MB_OK);
				//EndDialog(dlgst, ID_ST);
				break;
				case ID_CL:
					EndDialog(dlgst, ID_CL);
				break;
			}
		break;
		default:
			return FALSE;
	}
	return TRUE;
}

Sorry, I had to leave and do things - I meant to point out explicitly that you need to declare any variables that you expect to retain their values between function calls as static within your window procedure. Your combobox window handle is only a valid window handle within the context of the WM_CREATE, assuming CreateWindowEx does its job. Later, when a WM_COMMAND is handled it's not valid; I'm surprised you're getting anything short of rubbish from the CB_GETCURSEL. Confirm this for yourself by using IsWindow with the combobox handle in your WM_COMMAND handler.