Getting the old selected index in Winform's Combo box

Question

I have a combo box (winform). This combo box has some items (eg. 1,2,3,4).

Now, when I change the selection within this combo, I wish to know the old index and the new index.

How do I get this?

Possible approaches that I wish to AVOID.

Add an enter event, cache the current index and then on selection index change get the new index.
Using the selected text/selected item property received by the sender of the event.

What I ideally want:

In the event args that are received, I want something like:

e.OldIndex; e.newIndex;

Right now the event args which are received in the SelectionIndex Change event are totally useless.
I don't want to use more than one event.
If C#, does not offer this, can I have my event which passes the old index and new index as event args?

Hi Nikhil, you can do it using one variable and without any events, if you agree the idea tell me to Post the code as an answer. — Mahdi Tahsildari, Aug 23 '12 at 08:13
ComboBoxEdit by devexpress has EditValueChanging event.if you don't want to do anything with index and just want text property then it is better control than standard combobox. See http://documentation.devexpress.com/#WindowsForms/DevExpressXtraEditorsBaseEdit_EditValueChangingtopic — Ravi Patel, Aug 23 '12 at 08:20
possible duplicate of [ComboBox SelectedIndexChanged event: how to get the previously selected index?](http://stackoverflow.com/questions/3237885/combobox-selectedindexchanged-event-how-to-get-the-previously-selected-index) — Rawling, Aug 23 '12 at 08:20

score 6 · Accepted Answer · edited May 23 '17 at 12:06

6

Seems like this is a possible duplicate

ComboBox SelectedIndexChanged event: how to get the previously selected index?

There is nothing built in, you will need to listen for this event and keep track in a class variable.

But this answer seems to suggest a sensible way of extending the combobox to keep track of the previous index https://stackoverflow.com/a/425323/81053

edited May 23 '17 at 12:06

Community

1
1

answered Aug 23 '12 at 08:18

Chris Moutray

18,029
7
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66

score 0 · Answer 2 · answered Jan 04 '18 at 08:41

1-Make a List of integers
2-Bind a Button to switch to previous Screen (button Name "prevB")
3-change the ComboBox Index as Per described in the code

//initilize List and put current selected index in it

List<int> previousScreen = new List<int>();
previousScreen.Add(RegionComboBox.SelectedIndex);    

//Button Event
 private void prevB_Click(object sender, EventArgs e)
    {
        if (previousScreen.Count >= 2)
        {
            RegionComboBox.SelectedIndex = previousScreen[previousScreen.Count - 2];
        }
    }

score 0 · Answer 3 · answered Mar 06 '18 at 10:10

You will need to replace the ComboBox with the following control:

public class AdvancedComboBox : ComboBox
{
    private int myPreviouslySelectedIndex = -1;
    private int myLocalSelectedIndex = -1;

    public int PreviouslySelectedIndex { get { return myPreviouslySelectedIndex; } }

    protected override void OnSelectedIndexChanged(EventArgs e)
    {
        myPreviouslySelectedIndex = myLocalSelectedIndex;
        myLocalSelectedIndex = SelectedIndex;
        base.OnSelectedIndexChanged(e);
    }
}

Now you can get the PreviouslySelectedIndex property.

score 0 · Answer 4 · answered Jan 29 '20 at 15:55

0

You can use YourComboBox.Tag (or other unused string/int property) to store old selected index...

answered Jan 29 '20 at 15:55

Sergio Ross

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1
4

Thanks for your contribution! Please note however that the original author explicitly wanted to avoid caching (unless I misunderstood your answer). It is also great if you include code snippets with your answer. – mzuther Jan 29 '20 at 16:22

score 0 · Answer 5 · answered Mar 09 '21 at 11:23

0

I use such pair

comboBox.SelectedItem new item

comboBox.SelectionBoxItem old item

answered Mar 09 '21 at 11:23

Dmitrij

11
2

Getting the old selected index in Winform's Combo box

5 Answers5