1 void Main()
 2 {
 3     GetFWVersion().Dump();
 4 }
 5 
 6 static Version _version;
 7 public static Version GetFWVersion ()
 8 {
 9     if (_version != null) return _version;
10 
11     if (typeof (int).GetType ().BaseType.Name == "Type") return _version = new Version (4, 0);
12 
13     using (var key = Registry.LocalMachine.OpenSubKey (@"SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full"))
14     {
15         int? versionKey = key == null ? null : key.GetValue ("Release") as int?;
16         if (versionKey >= 461808) return _version = new Version (4, 7, 2);
17         if (versionKey >= 461308) return _version = new Version (4, 7, 1);
18         if (versionKey >= 460798) return _version = new Version (4, 7);
19         if (versionKey >= 394802) return _version = new Version (4, 6, 2);
20         if (versionKey >= 394254) return _version = new Version (4, 6, 1);
21         if (versionKey >= 393273) return _version = new Version (4, 6);
22         if (versionKey >= 379893) return _version = new Version (4, 5, 2);
23         if (versionKey >= 378675) return _version = new Version (4, 5, 1);
24     }
25     return _version = new Version (4, 5);
26 }