Question

Is there any registry key which i can look for wcf 4.0

Answer 1

Check out this blog post on how to detect .NET 4.0 – if you have .NET 4.0, you have WCF 4.0

Key     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Client
Name    Install
Type    REG_DWORD (32-bit integer)
Data    0x00000001 (1)

WCF is part of the "client profile" of .NET 4.0 – so this would be a check for WCF 4.0 (seems there are some more advanced WCF features which are not part of this – unfortunately, I don’t know for sure what those are).

Find more on the .NET 4 client profile in this MSDN library article.

If you need to detect the full .NET 4.0 (not just the client profile) check this:

Key      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full
Name    Install
Type    REG_DWORD (32-bit integer)
Data    0x00000001 (1)