Can I return a custom value from a dialog box's DoModal function?

Question

What I wish to do is, after creating a dialog box with DoModal() and pressing OK in the box to exit it, to have a custom value returned. For example, a couple of strings the user would input in the dialog.

Answer 1

You can't change the return value of the DoModal() function, and even if you could, I wouldn't recommend it. That's not the idiomatic way of doing this, and if you changed its return value to a string type, you would lose the ability to see when the user canceled the dialog (in which case, the string value returned should be ignored altogether).

Instead, add another function (or multiple) to your dialog box class, something like GetUserName() and GetUserPassword, and then query the values of those functions after DoModal returns IDOK.

For example, the function that shows the dialog and processes user input might look like this:

void CMainWindow::OnLogin()
{
    // Construct the dialog box passing the ID of the dialog template resource
    CLoginDialog loginDlg(IDD_LOGINDLG);

    // Create and show the dialog box
    INT_PTR nRet = -1;
    nRet = loginDlg.DoModal();

    // Check the return value of DoModal
    if (nRet == IDOK)
    {
        // Process the user's input
        CString userName = loginDlg.GetUserName();
        CString password = loginDlg.GetUserPassword();

        // ...
    }
}