Index was out of range. Must be non-negative and less than the size of the collection.

Question

1.00/5 (1 vote)

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This is my code:

VB.NET

Private Sub dgv_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles dgv.CellValueChanged

        dgv(e.ColumnIndex, e.RowIndex).Value = dgv(e.ColumnIndex, e.RowIndex).Value.ToString().ToUpper()

    End Sub

In code dgv means the datagridview.
There are 2 problems.
1 - I don't get any error in IntelliSense and this sub should work when value of a cell changed; but I get error at first of running.
2 - I've checked e.ColumnIndex and e.RowIndex with messagebox. Value of e.ColumnIndex starts from 0 and goes on with no problem; but value of e.RowIndex always equals -1.

The title of my question is the text of error.
Why? Where is my mistake?
Please help me

What I have tried:

I've tried to do that, with 2 nested for loop, but nothing happens.
I tested that code with CellLeave. In this way, i get first problem when i select any cell, title of error for second problem was changed as following:
Object reference not set to an instance of an object.

Posted 25-May-16 3:13am

Member 12127618

Updated 25-May-16 4:18am

v2

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Kenneth Haugland 25-May-16 9:25am

Is this WPF or WinForm?

Member 12127618 25-May-16 9:30am

WinForm

2 solutions

Solution 2

The solution is kind of easy. The RowIndex is -1 because there is no selected row. So, just check for that and if it's -1 return, don't do anything.

Next, you have to make sure that the index you're getting is actually a valid index for the range. So, check for it before you try to use an index that isn't in the range of valid values.

Posted 25-May-16 4:18am

Dave Kreskowiak

Comments

Member 12127618 25-May-16 11:19am

I have 21 rows. The code should wait until my selection; but i get problem at the first of running.

Dave Kreskowiak 25-May-16 11:35am

Yeah, and? I already told you how to defend against it.

Member 12127618 25-May-16 13:09pm

You said I have to make sure that the index is valid. I said I tried that and it returns -1.
So what else?
I didn't understand how to solve the problem.
Please Explain more
Thank you

Dave Kreskowiak 25-May-16 13:42pm

If it's not valid, you just return out of the method! You don't do anything with it.

Your code can only work with real index values. Anything outside of that range isn't valid and the code shouldn't do anything at all in that case.

Member 12127618 26-May-16 0:08am

Do you mean my problem does not have any solution?
Please look at this video:
https://youtu.be/bejVqkvsZPc?t=1525
I write his code in vb as you see in my code. For him it works.
All other part of code before this part was OK and exactly the same.

Dave Kreskowiak 26-May-16 0:35am

NO!! I keep telling you to check the index you get against the bound of the arrays before you try to look them up. It's that simple!

Member 12127618 26-May-16 1:13am

Please look at the video.
For him works for me not.
Why?

Dave Kreskowiak 26-May-16 9:30am

It works because he wrapped the code in a try/catch block that just ate the exception that the code would normally throw. This is BAD PRACTICE.

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Alan N · Accepted Answer · 2016-05-25T03:55:00

Solution 1

-1 is the index of the header row and CellValueChanged events with RowIndex = -1 are raised when a Column's HeaderText property changes. You probably have no interest in these events and can ignore them by testing for RowIndex = -1 in the handler.

For example:

VB.NET

Private Sub dgv_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles dgv.CellValueChanged
  If (e.RowIndex <> -1) Then 
    dgv(e.ColumnIndex, e.RowIndex).Value = dgv(e.ColumnIndex, e.RowIndex).Value.ToString().ToUpper()
  End If
End Sub

It may be that the events occur during column configuration and so deferring attachment of the CellValueChanged event handler until after the columns have been fully configured may be a solution.

Alan.

Posted 25-May-16 3:55am

Alan N

Updated 25-May-16 8:14am

v2

Comments

Member 12127618 25-May-16 11:25am

no, I don't want to handle a single event for RowIndex = -1.
I didn't understand what is your suggestion for me.
But if it is possible for you, instead of that, explain please, how to do following:
I want user put letter with all upper case. if user didn't, application do it for that cell.

Alan N 25-May-16 14:20pm

"I don't want to handle an event for RowIndex = -1"
You have no choice in the matter as the CellValueChanged event is raised for a change in ANY cell, including the header cells. The code in the handler must be written to exclude the header cells. I've added an example.

Member 12127618 26-May-16 0:29am

Thank you.
But I have another question. It's just a question for my knowledge.
With your example I can run with no problem, It changes user's write to uppercase, but I do not understand why it selects a whole row and at the first of running all of rows are selected.
Can you explain me please why?