c# Datagridview Row Calculation

Question

I have a windows form with a Datagridview in it containing data from an xml file. The DGV is setup like this: Date, Product, Price

There are 10 rows of data.

Im trying to calculate the change in Price from one row to the next and having difficulty finding a solution. For example:

1/1/12, ABC, $2.00
1/1/12, ABC, $2.50

Net Change: .50

Across columns I can use a Table.Columns.Expression, but it is unclear to me how I can do this calculation subtracting previous vs. current.

I thought about iterating through the columns, adding to a new table and calculating it that way, but seems like a sub-par solution. Once I get the change Id like to add that to that Datagridview.

Have not tested, but something like this:

if (dataGridView1.Rows.Count > 0)
{
    specifier = "###,###.00";

    double tier1Minus = 0;
    double tier2Minus = 0;

    for (int i = 0; i < dataGridView1.Rows.Count; ++i)
    {
        tier1Minus += Convert.ToDouble(dataGridView1.Rows[i].Cells["Price"].Value);

        tier2Minus += Convert.ToDouble(dataGridView1.Rows[i+1].Cells["Price"].Value);
    }

    // then add to dataGridView1
}

Answer 1

Why not just do something similar to (untested):

for(int i = 0; i < dataGridView1.Rows.Count - 1; i++)
    dataGridView1.Rows[i+1].Cells["NetChange"].Value =
        Convert.ToDouble(dataGridView1.Rows[i+1].Cells["Price"].Value) - 
        Convert.ToDouble(dataGridView1.Rows[i].Cells["Price"].Value);

Or better yet, calculate it the first time you import the data from the file and insert the rows.