What are the changes I need to make to a application built with .NET 2.0 /C# in order to use the C# 4.0 features . Recently I ran into a problem, when trying to add optional paramters in a product which was developed on .NET 2.0 / C# 2.0 .
Most 2.0 programs works without any changes on 4.0. It was only on 1.1 to 2.0 that there was a lot of incompatible changes.
One problem, that I ran into recently when upgrading a 3.5 project to 4.0 (Visual Studio 2008 to Visual Studio 2010), was that after upgrading to 4.0 I did not have a reference to System.Core and was unable to add it via Visual Studio instead displaying a message:
A reference to 'System.Core' could not be added. This component is already automatically referenced by the build system.
You will need to have a reference to System.Core if you want to use the var keyword and LINQ extension methods.
It can be manually added (or readded if removed). See the blog post System.Core in VS2010 Projects for details.
Maybe you migrated your Visual Studio solution to 2010, but you forgot to change the target framework to 4.0 in projects' properties.
Just go to properties in your solution projects (obviously, the migrated to Visual Studio 2010 solution) and change the target framework to 4.0.
That's all your C# code base will be using .NET Framework 4.0 and C# 4.0. I'm pretty sure you won't need to change your code, but, maybe, you'll find that some classes, methods, properties are now obsolete, but it'll compile anyway.
Comment out if you don't know how to do that.
In theory, C# 4 should be backwards compatible with C# 2.
In practice, I've done it several times with no problems, and I think the only obvious problem is if you have named some classes that are defined by the .net 4.0 framework.
You cannot use .NET 4.0 specific features in an application targeting .NET 2.0. You will need to migrate to .NET 4.0.
You can't easily convert form a higher version to a lower version.
You can easily convert form a lower version to a higher version.
C# in .NET 2.0 does not support optional parameters if I remember correctly.
Related
In preparation for moving to VS2015 I'm upgrading several solutions with CLR projects using the old (now deprecated) "old syntax" to rather use the "new syntax" (i.e. switch /CLR instead of /oldSyntax).
The C# projects are targeting .Net 3.5 (we were hoping to migrate to a later version as a separate step).
I have completed all the syntax stuff (and have no further errors/warnings in that respect), but on building receive the following error:
"SomeAssembly.dll", or one of its dependencies, requires a later version of the .NET Framework than the one specified in the project.
The errors are resolved if I update the C# projects to target .Net 4.0.
Is .Net 4.0 a minimum requirement for using the 'new syntax' (/CLR switch)?
I haven't been able to find any reference material mentioning this.
EDIT: The C# projects are all library projects.
EDIT: Building under VS2008 the error doesn't manifest, but it does when building under VS2015.
I don't find any where that dot net 4.0 is prerequisites for CLR switch, Just check your web.config accordingly before updating the C# projects to target .Net 4.0.
I have developed a program in visual studio 2012, my targeting framework was 4.5 and now i want it to be open in vs 2008.
I tried to edit cs file in notepad and edited it, but could not compile.
Is there any workaround?
Any help will be highly appreciated.
Visual Studio 2008 doesn't support the .NET 4.5 Framework. The maximum it supports is 3.5.
Similarly, the maximum VS 2010 supports is .NET 4.0.
You can try changing the target framework to 3.5 before opening it in VS2008, but if you're using anything from the newer frameworks, it won't compile.
Additionally, here's a Wikipedia article with the supported framework (and other information) for each Visual Studio release.
From ScottGu's blog: http://weblogs.asp.net/scottgu/archive/2009/08/27/multi-targeting-support-vs-2010-and-net-4-series.aspx
There isn't any way to target .NET 4 from VS08 and use new features.
Having said that, .NET4 is upwards comaptible with .NET 3.5 - so
applications you build targeting .NET 3.5 with VS08 should work fine
on top of .NET 4.
So in simple words you just can not!
Are you actually using features from the 4.5 framework? There's no IDE-supported way to do this, as other answerers have pointed out. What you can do is this:
Create a new project in Visual Studio 2008.
Add your files to it.
Go through and remove any references to .NET 4.5 and ensure it builds cleanly under .NET 2.0 or whatever VS2008-compatible framework you're targeting.
Rinse and repeat until you get a clean build.
Depending on what you're actually using in code, this may entail a lot of work or very little.
I am running Windows 8 and have both Visual Studio 2010 Ultimate w/sp1 and Visual Studio 2012 Ultimate and I am trying to create a Portable Class Library that supports .net 3.5 and greater.
When I first try to create a PCL I get a screen like this:
I noticed that .net 3.5 is not in the list so I clicked on "Install additional frameworks" and found a Targeting Pack for version 3.5. But when I download and run "dotnetfx35setup.exe" nothing happens. And when I go back into VS and try to create a new Portable Class Library, it lists the same target frameworks as before.
I have also turned on the Windows Features for .NET Framework 3.5 and am now out of ideas. Here is a screen shot in case I missed something else.
Thanks,
.NET Framework 3.5 didn't have a portable profile. Do you have this problem within Visual Studio 2010? I noticed once I installed Visual Studio 2012 on my own computer, the .NET Framework 3.5 was actually removed, likely because .NET 4.5 contains it.
Because you can still target to the .NET 3.5 if you want, just not a portable profile ( PCL ), which is easily proven by this article what you want is simply not supported.
As has been called out by others, .NET Framework 3.5 is not supported by portable library.
The link at the bottom of the page is a general landing page that lists all the targeting packs for all of our frameworks, not just the ones that work with portable, sorry for the confusion.
Visual Studio (either 2010 or 2012) allowed me to reference a simple Portable Class Library of Plain Old CLR Objects (POCOs) in another Class Library targeting .NET 3.5. This project works with Visual Studio 2015 as well.
It's possible that using some .NET 4.5 features in your PCL won't prevent it from compiling, but will make it incompatible for referencing from .NET 3.5.
When I try to do it I get the error "The application requires .NET Framework 3.5 SP1." I have .NET 4.0, how do I install 3.5 SP1? Can I have both?
Feel free to install all versions of .Net. They will not interfere with each other!
For adding dependencies to your project I recommend NuGet. Really handy and makes the project clean by adding references into it instead of requiring additional installation packages.
.Net 4.0 projects are capable of using .Net 2.0, .Net 3.0 and .Net 3.5 libraries. But note that projects running under ".Net 4.0 Client Profile" can have problems doing this, and you only get a misleading error when attempting to run the project. From within Visual Studio everything seems right.
Just like Tedd Hansen says you can sure have as many .NET versions as you want in your computer for it creates no conflict at all. I take it you are just trying to install something. If that's the case then you can always use this link to download the bootstrapper that will determine the right 3.5 verison for you (x86 or x64) and download and install it.
If you are developing an application you can change the target framework of the project by going to the project properties page and, in the compile tab, click on the "Advanced Compile Options" button. There you'll be able to choose.
And, also as Tedd mentions, you should avoid targeting the "Client Profile" versions unless you specifically know that the subsets present therein are sufficient.
On my machine (Windows 7 Enterprise x86) I have installed .Net framework 4.0 and Enterprsie Library 5.0 without any problems. Maybe some other issue you're facing?
IAdapter,
I've answered this already. See my answer and the workaround in the comment dtd Feb 5, 2011.
I am developing using 3.0 and VS 2008.
The problem is my build server does not have 3.5 installed and therefore I cant build the solution as MSBuild for 2.0 will not support the VS 2008 solution file.
There is no easy answer to this besides downgrading to VS 2005.
Any ideas folks?
VS2008 supports C# 3 - you may be using C# 3-specific features while still targeting .NET 2.0.
Is there a strong reason why you can't install .NET 3.5 on the build server? That would be my preferred solution, rather than regressing the version of VS you use.
You could probably automate downgrading the solution/project files - if you're not doing anything complicated, it'll just be a matter of changing version numbers - but it's not great to have the build server using a different compiler to the developers, IMO.
Since you have VS2008 projects and solutions you will need to install .NET 3.5 on you build server. Since you can still target .NET 3.0 or .NET 3.5 having .NET 3.5 installed on your build machine should not have any impact on the target environment.
Is it not possible to include the different versions without 'installing' them? In the repository can you add versioned .NET and point the build script to the version(I'm thinking like a submodule in Git) you want for that project? So instead of installing .NET 3.0, 3.5, 4.0, etc include the libraries?