程序代码：

void Main_OnCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
    switch(id)
    {
        case IDC_BUTTONADD:
        {
            TCHAR str1[256];
            int gettext=GetDlgItemText(hwnd,IDC_EDITADD,str1,sizeof(str1));
            if(0==gettext)
            {
                MessageBox(hwnd,TEXT("未填入任何项！"),TEXT("错误"),MB_OK|MB_ICONERROR);
                return;
            }
            HWND  hwndCombo1=GetDlgItem(hwnd,IDC_COMBO1);
            ComboBox_InsertString(hwndCombo1,0,str1);
            SetDlgItemText(hwnd,IDC_EDITADD,TEXT(""));
            MessageBox(hwnd,TEXT("添加成功！"),TEXT(str1),MB_OK|MB_ICONEXCLAMATION);
        }
        break;
        case IDC_BUTTONDEL:
        {
            HWND  hwndCombo1=GetDlgItem(hwnd,IDC_COMBO1);
            int intIndex=ComboBox_GetCurSel(hwndCombo1);
            if(CB_ERR==intIndex)
            {
                MessageBox(hwnd,TEXT("没有任何项被选中！"),TEXT("错误"),MB_OK|MB_ICONERROR);
                return;
            }
            ComboBox_DeleteString(hwndCombo1,intIndex);
            MessageBox(hwnd,TEXT("删除成功！"),TEXT(""),MB_OK|MB_ICONEXCLAMATION);
        }
        break;
        default:
        break;
    }
}