- open visual studio and click on project and choose ‘Properties’
- in ‘Build’ tab, choose ‘Advanced…’, check screen dump
- in language version, in dropdown list showing in screen dump, there is not ‘C#7’ and ‘C# 7.2’ for visual studio 2015
- in visual studio 2017, same dropdown list has ‘C# 7.x’ options
Although some ways could update visual studio 2015 to support C# 7, I higly recommand to use visual studio 2017.
