C# List without Elements of another List (set theory, complement)

Question

I got two List<Image> (ListA and ListB) and i need an efficient way to get the elements of ListA without the elements of ListB (A\B)

For example:

• ListA contains Image1, Image2, Image3, Image4
• ListB contains Image2, Image4
• ListA \ ListB would be Image1, Image3

I'm relatively new to C# and open for some suggestions

Answer 1

If items of ListA are unique you can put a simple Linq query:

  using System.Linq;

  ...

  List<Image> result = ListA
    .Except(ListB)
    .ToList();

If you want to modify existing list (i.e. ListA):

  ListA.RemoveAll(image => ListB.Contains(image));