c# Datagridview Row Calculation -

I have a Windows Form with a Datagrid Video that contains data from an XML file DGV is such an installation: Date, product, value

There are 10 rows of data

To calculate the change in price from one line to another and trying to find a solution. For example:

  1/1/12, change ABC, $ 2.00 1/1/12, ABC, $ 2.50 Net: .50   
 Columns You can use a table within. Columns Expression, but it is not clear to me that how can I reduce this calculation by past vs. existing  
 I thought that walking through the column, adding it to a new table and calculating like that, but seems like a sub-cross solution. Once I get the conversion ID, that datagrid visit Adding  
 has not been tested, but something like this:  
  if (dataGridView1.Rows.Count> 0) {specifier = "###, ## # 00 "; Double tier 1 minus = 0; Double Tier 2 Minus = 0; (Int i = 0; I & lt; Datagram View1.Rows.Count; ++ i) {Tier 1Minus + = Convert.ToDouble (DataGridView1.Rows [i]. ["Value"] Value.Tier2Minus + = Convert.ToDouble (DataGridView1.Rows [i + 1]. ["Value"] value.);} Then add data grid to View1}    
 
 
 Why not just some similar (untested):   
 Or better yet, the first time when you import data from the file do Its calculation so may include and insert rows,.