C# 6 Preview: Changes in VS2015 CTP 5

C# 6 and Visual Studio 2015 are both prerelease software at the moment, and thus they are subject to change at any time.

There have indeed been some changes in C# 6 that came out in CTP 5 but which don’t seem to have been mentioned anywhere.

String interpolation

If you’ve read my original article on string interpolation, you’ll know that the syntax was expected to change. Well, that has happened, and the expected syntax is now in place. So now, you can use string interpolation to write special formatted strings as follows:

            var name = "Chuck";
            var surname = "Norris";

            string message = $"The man is {name} {surname}";

The placeholders in the curly brackets no longer require a prefixing backslash, but a dollar sign is necessary at the start of the string to allow them to be interpreted properly.

Just like before, the placeholders are not restricted to simple variables. They may contain arbitrary expressions including properties and methods:

            var numbers = new int[] { 1, 2, 3, 4, 5 };

            string message = $"There are {numbers.Length} numbers, and their average is {numbers.Average()}";

You can use format strings in placeholders. Unlike in the original implementation, they don’t need to be enclosed in quotes if they contain operators (e.g. dashes which normally represent minus signs). However you need to be a little precise with them, as any extra space after the colon (:) appears in the output:

            var dateOfBirth = DateTime.Now;
            string message = $"It's {dateOfBirth:yyyy-MM-dd}!";

using static

I’ve also written about the using static feature before, which lets you declare a static class among the using statements and then omit the class prefix when using static methods.

The syntax has changed, and you will need to prefix the static class with the keyword “static” in the declaration. This is a good thing because it eliminates the confusion between which using statements are namespaces and which are static classes.

    using static System.Console;

    class Program
        static void Main(string[] args)
            WriteLine("Hello Lilly!");


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