Best Way To Determine If .NET 3.5 Is Installed

Question

I need to programatically determine whether .NET 3.5 is installed. I thought it would be easy:

<% Response.Write(Environment.Version.ToString()); %>
         


        

Answer 1

One option is to detect 4.0 using the version string:

    Environment.Version.CompareTo(new Version(4, 0));

then since 2.0 and 2.5 share a CLR version number, these need to be distenguished by checking the registry. Since those versions are released already, the strings to look for are known.