Question

When i load the file into the datagrid, i’m getting a error message, FormatException Error.
Here, what i’m trying to do, comparing the two cell vlaues, if the col index 2 value is greater than col index 3, then show a error message.

When iload the file for the first time, i have no issues. I fi load for the seconfd time, i'm gettign the above error message.

I tried using Convert.ToInt32, int, still i’m getting the same error message. How can i fix this??

private void datagridview_CellValidating(object sender, CellValidatingEventArgs e)
{
if (e.ColumnIndex != 0)
{
    if (e.RowIndex >= 0 && e.RowIndex < 8)
    {
        if (e.Value != null && datagridview.Rows[e.RowIndex].Cells[e.ColumnIndex - 1].Value != null)
        {
                //Convert.ToInt32, int////
            if (Double.Parse(e.Value.ToString()) <=
                Double.Parse(datagridview.Rows[e.RowIndex].Cells[e.ColumnIndex - 1].Value.ToString()))
            {
                MessageBox.Show("error");
                e.Cancel = true;
                datagridview.Rows[e.RowIndex].ErrorText = errorMesssage;
            }
        }
    }
}
}

Answer 1

I think you should revisit your condition here

if (Double.Parse(e.Value.ToString()) <=    
    Double.Parse(datagridview.Rows[e.RowIndex].Cells[e.ColumnIndex - 1].Value.ToString()))

Now what would happen when you are validating for Column1 the comparison would be with the value available in Column2 and Column1 (not as what you mentioned), so if the Value in Column1 cannot be parsed then it would pop up a format exception since it cannot be parsed.

So maybe you need to specify the columns in your if clause

if (e.ColumnIndex != 0) // here you allow for Column3, so that e.ColumnIndex - 1 is 2