New C# 7.0 features in Visual Studio “15” Preview 4
Visual Studio
Over the past couple of previews, new C# language features have been trickling in, but Preview 4 marks a point where the majority of C# 7.0 are now available.
Here’s a code sample that uses a good number of these features, and that works in Preview 4 today:
class Program
{
static void Main(string[] args)
{
object[] numbers =
{ 0b1, 0b10, new object[] { 0b100, 0b1000 }, // binary literals
0b1_0000, 0b10_0000 }; // digit separators
var (sum, count) = Tally(numbers); // deconstruction
WriteLine($"Sum: {sum}, Count: {count}");
}
static (int sum, int count) Tally(object[] values) // tuple types
{
var r = (s: 0, c: 0); // tuple literals
void Add(int s, int c) { r = (r.s + s, r.c + c); } // local functions
foreach (var v in values)
{
switch (v) // switch on any value
{
case int i: // type patterns
Add(i, 1);
break;
case object[] a when a.Length > 0: // case conditions
var t = Tally(a);
Add(t.sum, t.count);
break;
}
}
return r;
}
}
For a full write-up about tuples, deconstruction, pattern matching, local functions, and the rest of C# 7.0, head over to the .NET Blog.
Earlier versions of some of these features were shown at Build 2016.
Happy hacking!
 | Mads Torgersen, C# Language Program Manager @MadsTorgersen Mads leads the design of the C# language. During his 11 years at Microsoft he also contributed to Typescript, Roslyn, Visual Basic, and LINQ. Before that he was a professor at Aarhus University, doing research on programming languages and type systems. |
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