I've been using LINQ lately and I've been having a lot of fun with it. It makes working with collections so much better! Many thanks to "Pro LINQ by Joseph C. Rattz" (Amazon) - a great book to get you started on LINQ.
So I ran into a bit of a snafu yesterday and thought I would share some cool LINQ methods.
I was working on a Windows App and using a DataGridView to keep track of some information. I wanted to quickly search through the rows and determine if a rows "filename" column was already in the list. Naturally I wanted to "LINQafy" everything to get it done in one line of code. I quickly ran into the issue that DataGridView.Rows is a DataGridViewRowCollection so I couldn't use IQueryable<DataGridViewRow> because "Source is not IEnumerable<>"
So after a short time playing with DataGridView.Rows.AsQueryable() and also getting nowhere I noticed the Cast extension method. From there it was pretty easy to come up with a solution by reading the method signature:
DataGridViewRow dgvrow = grid.Rows.Cast<DataGridViewRow>().Where(r => r.Cells["filename"].Value.ToString() == filename).SingleOrDefault();
Now I have a reference to the DataGridViewRow (or null if it doesn't exist). It's very useful that using the Cast method will create an IEnumerable<T> so that you can easily do all your LINQ queries.