How to make assembly at lower framework

Question

I have vs 2010 installed on my machin.I am using one assembly(third party)in my project that assembly's class are not visble in my project.Same thing when I doing in office ,it is working fine.In office I have 2013.When I am making target framework 4.5 in office,working fine.How can I make assembly version to 4.0,because I can't upgrade vs 2013 now.It require time and net speed.I tried to upgrade framework 4.5,but my os windows 8.0 which already has.I am unable to see 4.5 under visual studio.What can I do now?

Answer 1

Check out this question Targeting .NET Framework 4.5 via Visual Studio 2010

Bottom line: it is unpractical to target .net 4.5 with vs 2010.

First answer says its impossible:

Visual Studio 2010 and beyond allow for targeting of prior framework versions but cannot be used for future releases. You must use Visual Studio 2012 in order to utilize .NET 4.5.

While second answer offers a ridiculously complicated solution:

There are pretty limited scenarios that I can think of where this would be useful, but let's assume you can't get funds to purchase VS2012 or something to that effect. If that's the case and you have Windows 7+ and VS 2010 you may be able to use the following hack I put together which seems to work (but I haven't fully deployed an application using this method yet).

This seems like an overkill to me, but you may check it out if you want.

As to your question about changing the .net version of the assambly to 4, it is impossible to change the .net version of a compiled dll. Check out answers to this question aswell: Why cant a .net 4.0 project reference a 4.5 assembly?