I'm getting this error: "Index -1 does not have a value." when clicking a combobox

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I'm getting this error when i click on the combobox (dropdown) the grid view in the winforms.

Index -1 does not have a value.

Please help me in this... I'm Stuck for a long time... No luck in googling. :(

Thanks.

Posted 4-Feb-13 22:02pm

Velrats

Updated 4-Feb-13 23:37pm

Joezer BH

v2

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Naveen.Sanagasetti 5-Feb-13 4:07am

post your code.. please

BotCar 5-Feb-13 4:12am

Not much we can do without seeing some code, but index -1 means nothing is selected. Hope that helps you figure it out.

BotCar 5-Feb-13 4:22am

I don't understand your comment. Can you please rephrase it?

Naveen.Sanagasetti 5-Feb-13 4:31am

for error explanation , they post some information that's enough...
But user asking in his question "Please help me in this... I'm Stuck for a long time... No luck in googling.", that's way i'm asking code, try to resolve where he facing the issue. that's want i'm asking yar...

Velrats 5-Feb-13 4:41am

I dont know where the error comes from... but I get the error message after loading the form.

2 solutions

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OriginalGriff · Answer 1 · 2013-02-04T22:49:00

Solution 1

When no item is selected, the index value that is returned by the SelectedIndex property is -1

At the top of your event handler check it before you use it:

C#

ComboBox cb = sender as ComboBox;
if (cb != null && cb.SelectedIndex >= 0)
   {
   ...
   }

Posted 4-Feb-13 22:49pm

OriginalGriff

Comments

Joezer BH 5-Feb-13 5:35am

5+, this one has required decryption work before producing an answer

Velrats 5-Feb-13 5:36am

I have the combobox inside the gridview. At that time how can I do this?? please explain....

OriginalGriff 5-Feb-13 5:49am

So? The error is occurring in an event handler method, no? And the event handler is presumably identifying the specific combobox? So change the code above to match the code you have!

glennPattonWork3 · Answer 2 · 2013-02-04T23:10:00

Hi,

Umm we really do need to see some code to help on this but a quick demo below:

C#

namespace WindowsFormsApplication160
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
   MessageBox.Show("index = "+comboBox1.SelectedIndex.ToString()+"\nvalue = "+comboBox1.Text);  
        }
    }
}

This will return -1 if there is no value in the Combo box when you read it. If you have data in it make sure it is shown. To show a value use the below:

C#

comboBox1.SelectedIndex = 1;

That will take the second value in the list of data that you have entered to the combo box Items value. For a full use of combo boxes in C# see
http://msdn.microsoft.com/en-us/library/system.windows.forms.combobox(v=VS.90).aspx[^]
Hope that helps.
Glenn