Ranges and indices

Another convenient functionality introduced in C# 8 is the new syntax to identify single elements or ranges inside a sequence. The language already offers the ability to get or set elements in an array using the square brackets and a numeric index, but this concept has been extended by adding two operators to identify an item from the end of a sequence and to extract a range between two indices.

In addition to the aforementioned operators, the base class library now offers two new system types, System.Index and System.Range, which we will immediately see in action. Let's consider an array of strings containing six country names:

var countries = new[] { "Italy", "Romania", "Switzerland", "Germany", "France", "England" };
var length = countries.Length;

We already know how to use the numeric indexer to get a reference to the first item:

Assert.IsTrue(countries[0] == "Italy");

The...