FindbyText versus FindbyIndex

I was working on this the other day.  At least, working a way to use the FindbyText and FindbyIndex features to get some of the heavy lifting I wanted done.  In this case I was using a combobox to manage selection options, had a dbgrid slaved to it to show deeper details for the one-line selection it provided, and have an option for individuals to indicate they wanted to save their option (out of a possible many) to a nearby listbox.  Now I wanted to be sure they didn't add multiples of the same type of selection from the combobox, a very common requirement, so I used FindbyText to search the item collection of the listbox.  In this case, I was looking for a "no match" result so I would know to add an item.  Here's a sample of the code:

    if (listbox.Items.FindByText(combobox.SelectedText) == null)
    {
        listbox.Items.Add(combobox.SelectedText);
    }

As you can guess, it returns a null value if nothing is found (not always the case, I might add).  If you are looking for a "match" then switch it to the following:

if (listbox.Items.FindByText(combobox.SelectedText) != null)

Just as a note, if you want to remove something that's been selected, say for a context menu or button that allows for it; or, for times when you have are looking for a positive find and want to take action, like removing a selected item from a list box, use the following line of code:

         listbox.Items.RemoveBySelection('Y');

It takes a boolean value, obviously and you could easily flip it to 'N'.  Good when you might need to toggle the ability to remove an item based on permissions.

Now, I realize I haven't covered FindbyIndex yet. you can use it to find items in a list or combo box thought its not as handy necessarily.  You would need to do the comparison outside first and then match it up by index and then perform a listbox.Items.FindbyIndex(Index).


Here is a much better use of findbyindex.  As a way to reset a combo/listbox back to its first entry:

    if(combobox.Items.Count > 0)
    {
        combobox.SelectedText = combobox.Items.FindByIndex(0);
    }