CODEWITHSUNDEEP
c#
user9969
user9969

Reputation: 16040

Hashset<string>contains for collection

I am comparing 2 hashsets full of filenames.I have successfully implemented "ExceptWith" but now I need to get a list of "all filenames that are in both sets."

I know hashset has a contains but that means looping the hashset for each item of the other one. Wondering if there is an inbuilt method to do this. I am doing with files with over 50000 filenames.

many thanks

Upvotes: 0

Views: 162

Answers (1)

driis
driis

Reputation: 164291

What you are talking about is a set intersection. There is a built in method for that:

HashSet<string> x = new HashSet<string> { "x", "a","b"};
HashSet<string> y = new HashSet<string> { "z", "a","b"};
x.IntersectWith(y);

Note that this modifies the original HashSet x. If you don't want that, use the extension method on Enumerable:

var intersection = x.Intersect(y);

Since the last one is defined as an extension on IEnumerable<T>, it works on the more general case as well. Just be aware that it might not be as optimized for performance as HashSet<T>.IntersectWith, since it needs to be able to work on all enumerables.

Upvotes: 3

Related Questions