这个想法由来已久,今天又碰上有人问我这个问题,使出吃奶的劲尔狠狠的google的一番,
有如下结果,供后来人参考
How to check the version of the dotnet framework installed.
How To Verify .Net Framework Version Environment.Version Property (System)
Get the .NET Framework Fast - Download the smallest .NET Framework Distribution possible
How to Check What Version of Microsoft .NET Framework is Installed in Computer » Raymond.CC Blog ASoft .NET Version Detector.
Innosetup script to detect dotnet framework and old version
本文参考链接：https://www.cnblogs.com/lexus/archive/2009/12/09/1619912.html
