Determine if a List contains elements from another List

Question

I have an object model MyObject that contains a list of long called ObjectList . I have another list called TestList that also contains longs and I want to determine if TheObject.ObjectList contains any elements that are in TestList .

I'm trying with something like this but it's not giving Count as an option.

if (TheObject.ObjectList.Any(TestList).Count() > 0) {...}

How should I rewrite this? Thanks for your suggestions.

Answer 1

Use Intersect :

TheObject.ObjectList.Intersect(TestList).Any()

Produces the set intersection of two sequences by using the default equality comparer to compare values.

Note: There are also Except and Union set opeartions.

Answer 2

 if ( TheObject.ObjectList.Intersect(TestList).Any() ) 
 { 
   ... 
 }