Question

This just for general knowledge:

If I have two, let’s say, List, and I want to iterate both with the same foreach loop, can we do that?

Edit

Just to clarify, I wanted to do this:

List<String> listA = new List<string> { "string", "string" };
List<String> listB = new List<string> { "string", "string" };

for(int i = 0; i < listA.Count; i++)
    listB[i] = listA[i];

But with a foreach =)

Answer 1

This is known as a Zip operation and has been supported since .NET 4.

With that, you would be able to write something like:

var numbers = new [] { 1, 2, 3, 4 };
var words = new [] { "one", "two", "three", "four" };

var numbersAndWords = numbers.Zip(words, (n, w) => new { Number = n, Word = w });
foreach(var nw in numbersAndWords)
{
    Console.WriteLine(nw.Number + nw.Word);
}

---

As an alternative to the anonymous type with the named fields, you can also save on braces by using a Tuple and its static Tuple.Create helper:

foreach (var nw in numbers.Zip(words, Tuple.Create)) 
{
    Console.WriteLine(nw.Item1 + nw.Item2);
}