Find the intersection of two lists in linq?

Question

I have list of int A,B. i like to do the following step in linq

list c = new List();

for (int i = 0; i < a.count; i++)
{
    for (i         


        

Answer 1

The LINQ equivalent of your code is:

var c = from i in Enumerable.Range(0, a.Count)
        from j in Enumerable.Range(0, b.Count)
        where a[i] == b[j]
        select a[i];

var cList = c.ToList();

But it's much nicer to do:

var c = from aItem in a 
        join bItem in b on aItem equals bItem
        select aItem;

var cList = c.ToList();

But this doesn't filter duplicates. To filter duplicates completely, you can do:

var cList = a.Intersect(b).ToList();

If you want duplicates to show up as many times as they do in b, for example:

var aSet = new HashSet(a);
var cList = b.Where(aSet.Contains)
             .ToList();