Intersect two List<> in C#

问题

I have two List<T> objects that I would like to intersect, but I get errors when trying.

// Make the Keys in the Dictionary<Load, double> _loads to form a List<Load>
List<Load> l1 = _loads.Keys.ToList();

// Get a list from my element.
List<Load> l2 = element.ListLoads;

// Intersect
List<Load> loads = (List<Load>)l1.Intersect<Load>(l2);

回答1:

Intersect<T> returns an IEnumerable<T>, so the correct way is:

var loads = l1.Intersect(l2).ToList();

ToList<T> creates a List<T> from an IEnumerable<T>.

Note that you can omit the type argument when invoking Intersect<T>, the compiler is smart enough to infer it.

回答2:

You can do it this way:

List<Load> loads=new List<Load>(l1.Intersect(l2));

This is because Intersect will return an IEnumerable and this is the right way to create a new list from an IEnumerable.

来源：https://stackoverflow.com/questions/11383329/intersect-two-list-in-c-sharp