Why can't this cast be done?

Question

5.00/5 (2 votes)

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I don't have a programming problem, but I'd like to know why.

I have something like this

List<MyClass> a,b,c<br /><br />var d = a.Except(b);<br />c.Clear()<br />c = d.ToList();

Of course, lists a & b are populated preceding the code. The question is, why can't I cast directly to List<myclass> as such:

<br />c = a.Except(b);<br />

Posted 5-Aug-09 1:00am

2 solutions

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Pete O'Hanlon · Accepted Answer · 2009-08-05T03:37:00

You can't cast it as such because a.Except(b) returns the type System.Linq.Enumerable.ExceptIterator. You have two options here:

c.AddRange(a.Except(b));

or

c = a.Except(b).ToList();

Posted 5-Aug-09 3:37am

Comments

Nish Nishant 27-Jul-10 9:52am

Reason for my vote of 5
Great answer.

TheGreatAndPowerfulOz · Accepted Answer · 2010-04-06T15:39:00

because they're basically different types. a.Except(b) does not return a list, it returns an "Enumerable" type.

so

IEnumerable c
List a,b

c = a.Except(b)

will work

Posted 6-Apr-10 15:39pm