Linq C# indexを取る

まずこれは行ける。

var ordinals = new string[] { "First", "Second", "Third" };
var indexed = ordinals.Select((n, i) => new { Index = i, Ordinal = n })
    .Select((e) =>
    {
        Debug.Log(e.Index);
        Debug.Log(e.Ordinal);
        return e;
    }).ToArray();

"First"
0
"Second"
1
"Third"
2

これも行ける。

var indexed = ordinals
    .Select((e, i) =>
    {
        Debug.Log(e);
        Debug.Log(i);
        return e;
    }).ToArray();

"First"
0
"Second"
1
"Third"
2