CODEWITHSUNDEEP
c#winformsformscombobox
Idanis
Idanis

Reputation: 1988

Check if a ComboBox value is selected

I'm writing a form which includes some buttons and a combo box. The "Ok" button is disabled by default, and I wish to enable it only after an actual value (not the combo box's name) is selected.

I know how to access the selected value, and how to check if a value has been selected - but these two can be done only after the form is close (using the"x" or using the "ok" button - which is disabled).

Any ideas?

Thanks.

Upvotes: 5

Views: 34737

Answers (3)

rs.
rs.

Reputation: 27427

You can use combobox selected index changed event

Add this to your InitializeComboBox class

this.ComboBox1.SelectedIndexChanged += 
            new System.EventHandler(ComboBox1_SelectedIndexChanged);

then in selected index changed event you can check if combox box is selected

private void ComboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
   ComboBox cbx= (ComboBox) sender;
   Button1.Enabled = !string.IsNullOrEmpty(cbx.SelectedItem.ToString());
}

Upvotes: 0

spajce
spajce

Reputation: 7082

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (comboBox1.SelectedIndex == -1)
            button1.Enabled = false;
        else
            button1.Enabled = true;

        //or
        //button1.Enabled = comboBox1.SelectedIndex == -1;
    }

Upvotes: 0

Mitch
Mitch

Reputation: 526

Perhaps like this:

    private void comboBox_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (comboBox.SelectedIndex > -1)
        {
            buttonOK.Enabled = true;
        }
    }

By default a combobox's selected index is -1 (the combobox's name, which you can't reselect after choosing another index), so if you check that it's not -1 then you know a value has been selected.

However another alternative, and the one I use, is if I always want a value to be selected is to use the DropDownStyle property and set it to DropDownList. That way index 0 is selected by default and the user can only select items from the list and nothing else.

Upvotes: 8

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