How to solve error: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

Hi Kavithale

You have to remove the '=' in the for loop.

b'cos "i" value is starting from 0. for example, if u have 10 records in a gridview. you have to consider 0 to 9

for (int i = 0; i < gridview.Rows.Count; i++)
{
    if (!xxx.equals(gridview.Rows[i].Cells[0].Text))
    {
        dr = dt.NewRow();
        dr[0] = */adding value*/
        dt.Rows.Add(dr);
    }
}

My suggestion is you can use foreach iterator statement to travarse gridview.
Instead of that

for (int i = 0; i <= gridview.Rows.Count; i++)
{
    if (!xxx.Equals(gridview.Rows[i].Cells[0].Text))
    {
        dr = dt.NewRow();
        dr[0] = */adding value*/
        dt.Rows.Add(dr);
    }
}

You can use

 foreach (GridViewRow row in gridview.Rows)
 {
    if (!xxx.Equals(row[i].Cells[0].Text))
    {
        dr = dt.NewRow();
        dr[0] = */adding value*/
        dt.Rows.Add(dr);
    }
}

It is more cleaner and readable. It will safe us for accidental errors like you faced < vs <= etc problem. I always prefer foreach to navigate list where list implement iterator pattern.