How to calculate NETWORKDAYS in C#

I use this project mainly as a learning exercise for DataSet and LINQ.

The background is that I have a report in Excel html format that I read into a .NET 3.5 C# Windows Forms Application. I then display the data in a DataGridView and I also want to calculate some statistics on the data. To do so, I need to add a new column showing the elapsed number of working days between two dates.

In my DataSet, I have two columns, "Open Date" and "Close Date". In Excel I was able to use a formula like "=NETWORDAYS(B7:C7, Z2:Z50) to calculate the number of working days elapsed between the two dates.

Is there an easy way of achieving the same thing in my C# code, adding a new column to my DataTable?

The code needs a bit more polishing, eg. adding some error trapping etc but it shows what I have at the moment.

private void GetDataFromExcel(string fileName)
		{
			String connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;data source=" + fileName + ";Extended Properties=HTML Import;";
 
			OleDbConnection dbConnection = new OleDbConnection(connectionString);
			dbConnection.Open();
 
			string select = @"SELECT * FROM [Table]";
 
			OleDbCommand selectCommand = new OleDbCommand(select, dbConnection);
 
			OleDbDataAdapter dbDataAdapter = new OleDbDataAdapter();
 
			dbDataAdapter.SelectCommand = selectCommand;
 
			DataSet ds = new DataSet();
 
			dbDataAdapter.Fill(ds, "XLData");
 
			mainDataGridView.DataSource = ds.Tables[0];
 
			dbConnection.Close();
 
		}

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