If you are starting with something that has a .Length or .Count (such as ICollection<T>, IList<T>, List<T>, etc) – then this will be the fastest option, since it doesn’t need to go through the GetEnumerator()/MoveNext()/Dispose() sequence required by Any() to check for a non-empty IEnumerable<T> sequence. For just IEnumerable<T>, then Any() will generally be quicker, … Read more
It really depends on whether or not you can trust s.Length. For many streams, you just don’t know how much data there will be. In such cases – and before .NET 4 – I’d use code like this: public static byte[] ReadFully(Stream input) { byte[] buffer = new byte[16*1024]; using (MemoryStream ms = new MemoryStream()) … Read more
You can’t query against the DataTable‘s Rows collection, since DataRowCollection doesn’t implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so: var results = from myRow in myDataTable.AsEnumerable() where myRow.Field<int>(“RowNo”) == 1 select myRow; And as @Keith says, you’ll need to add a reference to System.Data.DataSetExtensions AsEnumerable() returns IEnumerable<DataRow>. If you need … Read more
What if I want to obtain a distinct list based on one or more properties? Simple! You want to group them and pick a winner out of the group. List<Person> distinctPeople = allPeople .GroupBy(p => p.PersonId) .Select(g => g.First()) .ToList(); If you want to define groups on multiple properties, here’s how: List<Person> distinctPeople = allPeople … Read more