How can I change C# version from 7.0 to 6.0

I'm working on my project with my friends, I use some feature from 7.0 such as tuples but errors occur on my friend's device it said: Feature 'tuples' cannot be used because it is not part of the C# 6.0

So I want to revert it back to 6.0 because I can't remember all where I used 7.0 syntax

 

Something doesn't sound right. What version of Unity are you using? C# 7 Support isn't scheduled until 2018.3, which isn't in beta yet, so I wouldn't think you could possibly be writing C# 7 syntax.

Sounds more likely that you're using .NET 4.x, and your friend's project is using .NET 3.x. Tuples have existed before C# 7. (C# 7 just adds more funtionality for tuples). For example, this is totally valid under C# 6:

Code (CSharp):

1. Tuple<string, string> x = new Tuple<string, string>("","");

So I'm guessing you're on 4.6, and you need to change it down to 3.5.

Go to Edit -> Project Settings -> Player, and go to the Other Settings area. Change the Scripting Runtime Version.

 

I've changes codes to not use tuple, and I also want to use ECS but still have problems like as the image: https://imgur.com/a/VpgLw3t
So I think I should to something to make it use C# 7.0

Now using Unity 2018.4.1

 

Tuple and ValueTuple are something completely different though.

There's also the new ValueTuple syntax in c#7.

And if he's using the incremental compiler package or ECS (which implicitly pulls in the incremental compiler) he might be able to use c#7 syntax.

 

About tuples, I've used it's syntax it like this https://blogs.msdn.microsoft.com/mazhou/2017/05/26/c-7-series-part-1-value-tuples/

 

Oh, I will tell my friend to install incremental compiler