Why can't we debug a method with yield return for the following code? [duplicate]

Answer 1

You can debug the method. The problem is, the code that you are trying to reach is never executed.

IEnumerable methods with yield return produce code that makes your sequence lazily, as you go through enumeration. However, when you do this

var sn = FilterWithYield();

you prepare to enumerate the sequence, but you do not start enumerating it.

If, on the other hand, you add a foreach loop or call ToList() on the result, your breakpoint would get hit:

foreach (var n in FilterWithYield()) {
    Console.WriteLine(n);
}

or

var sn = FilterWithYield().ToList();