Question

I have a collection.

I want to project from it only first N that are not deleted.

However I want to count how many elements (deleted and non-deleted)
I traversed till got to the Nth non-deleted element.

How can I do it?
i thought to use side effect:

int i;
collectiom.Skip(Convert.ToInt32(startIndex))
            .TakeWhile( x=> 
{
++i != 0; 
return (!x.IsDeleted)
})
            .Take(N);

But the compiler refuses.
And now I see it’s not answering my need anyway

TIA

Answer 1

How about this:

var selected = collection.Select((x, i) => new {Item = x, Index = i})
                         .Skip(Convert.ToInt32(startIndex))  
                         .Where(x => !x.Item.IsDeleted)
                         .Take(N);

The result is a sequence of N anonymous objects where x.Item is the original object, and x.Index is its index in the original collection. If you want to start counting the original collection from startIndex just swap the Select and Skip calls.

You can then get the number you want like so:

var numberProcessed = selected.Last().Index + 1;