CODEWITHSUNDEEP
linqlinq-to-sqlc#-4.0
shiv455
shiv455

Reputation: 7764

Remove an item in List if not exists in other list using linq

I have two different types of Lists

class A

{

int number;

string name;

}

class B

{

int number;

}

List<A> a1;

List<B> b1;

And now both the lists were populated and now i want to remove items(number) in list a1 if that item(number) not exists in list b1.tried the below approach

a1.removeall(a=>b1.Exists(b1.number!=a1.number);

but the result is not as expected.Please help me...

Upvotes: 0

Views: 4234

Answers (1)

BrokenGlass
BrokenGlass

Reputation: 160912

I think you want this:

a1.RemoveAll(a=> !b1.Any(b=> b.number == a.number));

Be aware though that this is O(n^2). A more performant approach would be using a HashSet<int> (this might not matter for small lists but be aware of this for larger ones):

 HashSet<int> bNums = new HashSet<int>(b1.Select(b => b.number));
 a1.RemoveAll(a => !bNums.Contains(a.number));

Upvotes: 5

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