Switch case and generics checking

Question

I want to write a function that format int and decimal differently into string

I have this code:

and I want to rewrite it to generi

Answer 1

Alternatively you could always do:

public static string FormatWithCommaSeparator(T[] items)
{
    var itemArray = items.Select(i => i.ToString());

    return string.Join(", ", itemArray);
}