what is the C# compiler option for specifying the version of .net framework

Question

I have look completely in this two msdn article C# Compiler Options Listed Alphabetically and C# Compiler Options Listed by Category for compiler option for specifying the target framework version which can be used in command line building. I got to know that we can specify the framework version in app.config with supportedRuntime element.

Can we use this element(configuration>startup>supportedRuntime) in web.config also(in case of asp.net application) ?

I have not needed to do it with only command line switch. I just asking this question only because of curious to know about it.

Answer 1

The compiler doesn't care about what version of the framework, only the version of the runtime and the language.

The cl.exe program just compiles and links whatever you throw at it, and it is up to you to add references to .NET 4.5-specific assemblies or not. You can choose to reference older versions of external references by specifically asking for a version using a fully qualified assembly name.

The setting in Visual Studio is just a filter that shows/hides assemblies when you are adding references.