By default C# 7.0 was shipped with Visual Studio 2017 and this was the major release (March 2017) until now. In August 2017 a minor version of C# 7.0 was released, named C# 7.1. This minor version came with four new features (async main, target-typed default literals, tuple name inference, and generic support for pattern-matching) and some minor changes to what was introduced in C# 7.0.
Here, in this article, we will discuss how to make sure your existing projects point to the new C# language i.e., C# 7.1. To do this we have three approaches.
Approach 1 - Using Project Properties
In this approach, go to your existing project where you want to point to C# 7.1 and open project properties by right clicking on the project. Select properties in Visual Studio Solution Explorer window as below