How to Get a Sublist in C#

Question

I have a List<String> and i need to take a sublist out of this list. Is there any methods of List available for this in .NET 3.5?

Answer 1

You want List::GetRange(firstIndex, count).

// I have a List called list
List sublist = list.GetRange(5, 5); // (gets elements 5,6,7,8,9)
List anotherSublist = list.GetRange(0, 4); // gets elements 0,1,2,3)

Is that what you're after?

If you're looking to delete the sublist items from the original list, you can then do:

// list is our original list
// sublist is our (newly created) sublist built from GetRange()
foreach (Type t in sublist)
{
    list.Remove(t);
}

Answer 2

Would it be as easy as running a LINQ query on your List?

List<string> mylist = new List<string>{ "hello","world","foo","bar"};
List<string> listContainingLetterO = mylist.Where(x=>x.Contains("o")).ToList();

Answer 3

With LINQ:

List<string> l = new List<string> { "1", "2", "3" ,"4","5"};
List<string> l2 = l.Skip(1).Take(2).ToList();

If you need foreach, then no need for ToList:

foreach (string s in l.Skip(1).Take(2)){}

Advantage of LINQ is that if you want to just skip some leading element,you can :

List<string> l2 = l.Skip(1).ToList();
foreach (string s in l.Skip(1)){}

i.e. no need to take care of count/length, etc.

Answer 4

Use the Where clause from LINQ:

List<object> x = new List<object>();
x.Add("A");
x.Add("B");
x.Add("C");
x.Add("D");
x.Add("B");

var z = x.Where(p => p == "A");
z = x.Where(p => p == "B");

In the statements above "p" is the object that is in the list. So if you used a data object, i.e.:

public class Client
{
    public string Name { get; set; }
}

then your linq would look like this:

List<Client> x = new List<Client>();
x.Add(new Client() { Name = "A" });
x.Add(new Client() { Name = "B" });
x.Add(new Client() { Name = "C" });
x.Add(new Client() { Name = "D" });
x.Add(new Client() { Name = "B" });

var z = x.Where(p => p.Name == "A");
z = x.Where(p => p.Name == "B");