Convert ICollection<T> to List<T>

The easiest way to convert a ICollection to a List is the usage of LINQ like (MSDN)

List<T> L = C.ToList();

Dont't forget to add

using System.Linq;

otherwise ToList() is not available.

You can supply the collection as an argument in the List<T> constructor:

List<DataStructure> lst_DataStructure = new List<DataStructure>(list_Stuctures);

Or use the .ToList() extension method, which does exactly the same thing.

Keep it simple, ToList:

List<DataStructure> lst_DataStructure = list_Stuctures.ToList();