How to most elegantly iterate through parallel collections in C#?

Question

        var a = new Collection<string> {"a", "b", "c"};
        var b = new Collection<int> { 1, 2, 3 };

What is the most elegant way to iterate through both yielding a set of results "a1", "b2", "c3"?

Answer 1

This is known as "zipping" or "zip joining" two sequences. Eric Lippert describes this very algorithm and provides an implementation.

Answer 2

The mighty Bart de Smet talks about zip functions here:

http://community.bartdesmet.net/blogs/bart/archive/2008/11/03/c-4-0-feature-focus-part-3-intermezzo-linq-s-new-zip-operator.aspx

His most elegant solution takes advantage of an overload of select that takes a 2 parameter Func delegate as its parameter.

a.Select((t,i)=>new{t,i});

In this example, i simply represents the index of the item being processed. So you can create 2 new enumerables of these anonymous objects and join them on i.

Performance-wise, I'd go with a more obvious yielding loop.