reading from ComboBox - c++

Question

how can i read the text of a selected value of a comboBox in windows aplication(borland C++) for example:
i have combobox which contains 2 values (sum and mult) i want to see if it is sum i have to add the numbers and if it mult i have to multiplicate the numbers so how can i read the value of combobox in this case.

Answer 1

For Windows:
In your window procedure use the WM_COMMAND message and then check for a CBN_SELCHANGE notification. Then use WM_GETTEXT along with WM_GETTEXTLENGTH to receive the selected text like Mark Ingram says. Or you can also use CB_GETCURSEL to receive the identifier of the selected item.
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
case WM_COMMAND:
switch(LOWORD(wParam)) {
case IDC_COMBO:
if (HIWORD(wParam) == CBN_SELCHANGE) {
HWND hCtl = GetDlgItem(hWnd, IDC_COMBO);//Get handle for HMENU item
if (SendMessage(hCtl, CB_GETCURSEL, 0, 0) == compareValue) {
//...
}
}
break;
}
break;
//...
}
}

Answer 2

Assuming that you are using Windows, you can use the following messages:
WM_GETTEXTLENGTH and WM_GETTEXT.
Firstly, get the length of the selected text, then allocate your buffer to ensure it's large enough, then retrieve the actual text. Easy.
Example:
const UINT length = ::SendMessage(hWnd, WM_GETTEXTLENGTH, 0, 0);
LPTSTR pszText = new TCHAR[length + 1];
::SendMessage(hWnd, WM_GETTEXT, length + 1, pszText);
// pszText will now contain the text you want, do what you want with it
delete[] pszText; // Remember to delete else you will leak.

Answer 3

I never work with c++ with winapplication but i tried it with the c# and hopefully that you want the desired output as i got through your question if it is not right then you should edit your question.
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (comboBox1.Text == "ADD")
{
int a = 12, b = 13, c;
c = a + b;
MessageBox.Show("Result of adding= " + c);
}
else if (comboBox1.Text == "Multiple")
{
int x = 3, y = 5, z;
z = x * y;
MessageBox.Show("Result of multiplication= " + z);
}
}