retrieving data from listboxes

hello,
i'm working on a small app with a listbox, and i'm looking for a way to display the users selection. It's a dialog application, and i'm using a single-selection listbox.
I've tried this, but without success:

Code:

---

       
        case WM_COMMAND:
                switch(LOWORD(wParam))
                {
                case IDC_LIST:
                        switch(HIWORD(wParam))
                        {
                        case LBN_SELCHANGE:
                                LRESULT selection = SendMessage(hWnd, LB_GETTEXT, 0, 0);
                                SetDlgItemText(hWnd, IDC_TEXT, (LPCSTR)selection);
                                break;
                        }
                        break;
                }
                break;

---

Any ideas what i'm doing wrong?

I believe that you are using LB_GETTEXT incorrectly. You need to pass a character buffer in the lParam of SendMessage.

thanks for your reply,
I tried your idea, but it seems like i'm doing something else wrong now :confused: . here's the new code:

Code:

---

        case WM_COMMAND:
                switch(LOWORD(wParam))
                {
                case IDC_LIST:
                        switch(HIWORD(wParam))
                        {
                        case LBN_SELCHANGE:
                                {
                                        char* buf;

                                        LRESULT len = SendMessage(hWnd, LB_GETTEXTLEN, 0, 0);
                                        buf = (char*)GlobalAlloc(GPTR, len+1);

                                        SendMessage(hWnd, LB_GETTEXT, 0, (LPARAM)buf);
                                        SetDlgItemText(hWnd, IDC_TEXT, buf);

                                        GlobalFree((HANDLE)buf);
                                }
                                break;
                        }
                        break;
                }
                break;

---

Is hWnd your listbox?

ehm.. i haven't thought about that :o
i'm pretty new to this API programming, but i've tried to do as you said, but it still dosen't work :(. here's the new code:

Code:

---

    case WM_COMMAND:
        switch(LOWORD(wParam))
        {
        case IDC_LIST:
            switch(HIWORD(wParam))
            {
            case LBN_SELCHANGE:
                HWND hList = GetDlgItem(hWnd, IDC_LIST);

                char* buf;

                LRESULT len = SendMessage(hList, LB_GETTEXTLEN, 0, 0);
                buf = (char*)GlobalAlloc(GPTR, len+1);

                SendMessage(hList, LB_GETTEXT, 0, (LPARAM)buf);
                SetDlgItemText(hWnd, IDC_TEXT, buf);

                GlobalFree((HANDLE)buf);
                break;
            }
            break;
        }
        break;

---

Do you have the LBS_NOTIFY or LBS_STANDARD style? (or will not get the selection change msg).

Place a break point (or messagebox) to ensure that this section of the callback is receiving messages.



Try something like

Code:

---


int iSelected = SendMessage( hList, LB_GETCURSEL , 0, 0 );//get current selection
if(iSelected != LB_ERR) // found a selected item
{
        LPTSTR lpsText;
        SendMessage(hList, LB_GETTEXT, (WPARAM)iSelected, (LPARAM)lpsText);//add return error check
}

---

This explains what the LPTSTR data type is.
MSDN
"The letter T in a type (for example, TCHAR, LPTSTR) definition designates a generic type that can be compiled for either Windows code pages or Unicode."

http://msdn.microsoft.com/library/de...icode_28c3.asp

thanks, novacain. it all works now :)