While C# as a language has grown leaps and bounds, one are that was least addressed was manipulation of collections (arrays in particular). C# 8 looks to change exactly that by introducing two new Types.
System.Index is a structure that can be used to Index a collection either from the start or the end. In previous versions of the language, there was no direct way to index a collection from the end. For example,
// Get the 2nd element from end in the array var secondElementFromLast = arr[arr.Length-2];
This changes with introduction of the System.Index, which fortunately is introduced with its own syntatic sugar. The code above, for accessing the second last element could be now rewritten as
// Get the 2nd element from end in the array var secondElementFromLast = arr[^2]; // With the uniary prefix 'hat' operator
To access the elements from the begining of the array, you could use
// Get 2nd element from the start in the array var secondElementFromStart = arr; // No changes here
In previous versions of C#, there was no easy way to get a slice of the collection. Let’s say, you wanted to get all elements from 2nd to 5th element in the array. You could achieve this using Linq using the Enumerable.Skip and Enumerable.Take methods. For example
var slice = list.Skip(1).Take(4);
C# 8.0 introduces the System.Range type, again with support of syntatic sugar to ease the life of developers. The above code could now be rewritten as
var slice = list[1..5];
The Range Structure represents range that has a start and end indexes and is represented by binary infix
x..y. Do note that both operands of the range could be ommited to provide different meanings. For example
var slice1 = list[5..]; // All elements starting from the 5th element in collection var slice2 = list[..5]; // First 5 elements in collection var slice3 = list[..^5]; // Elements starting from first till the 5th element from last var slice4 = list[^5..]; // Last 5 elements in collection var slice5 = list[..]; // Entire List
We will continue exploring newer features of the language in coming blog posts.