I am newbie to the .NET Framework. I have some a question about .NET program execution.
If I am developing a .NET application using .NET Framework version 4.0, can that application be run on .NET framework 3.5 ? Are there any compatibility issues are there?
For example If I develop a dll using .NET framework 4.0, can it be referenced by another programme which is using .NET framework 3.5?
.Net Framework is generally backward compatible, so you can load a .Net 3.5 assembly in a .Net 4 runtime, but not vice-versa.
You should target your assemblies at the lowest supported version of the runtime.
Here is some additional reading that should answer most of your questions...
https://msdn.microsoft.com/en-us/library/ff602939(v=vs.110).aspx
No, you cannot reference a DLL compiled in .NET 4.0 from a program compiled in .NET 3.5. .NET Framework applications are usually backward compatible -- that is, you can reference a .NET 3.5 assembly from .NET 4.0 code, but the reverse is not true.
You could try compiling the .NET 3.5 project in 4.0, or compiling the .NET 4.0 assembly in .NET 3.5, either of which will work if they are an option.
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I am newbie to the .NET Framework. I have some a question about .NET program execution.
If I am developing a .NET application using .NET Framework version 4.0, can that application be run on .NET framework 3.5 ? Are there any compatibility issues are there?
For example If I develop a dll using .NET framework 4.0, can it be referenced by another programme which is using .NET framework 3.5?
.Net Framework is generally backward compatible, so you can load a .Net 3.5 assembly in a .Net 4 runtime, but not vice-versa.
You should target your assemblies at the lowest supported version of the runtime.
Here is some additional reading that should answer most of your questions...
https://msdn.microsoft.com/en-us/library/ff602939(v=vs.110).aspx
No, you cannot reference a DLL compiled in .NET 4.0 from a program compiled in .NET 3.5. .NET Framework applications are usually backward compatible -- that is, you can reference a .NET 3.5 assembly from .NET 4.0 code, but the reverse is not true.
You could try compiling the .NET 3.5 project in 4.0, or compiling the .NET 4.0 assembly in .NET 3.5, either of which will work if they are an option.
I have an assembly that is compiled with .NET 3.5. I cannot recompile it in .NET 4.5 since it is used in other applications that are still running .NET 3.5. When I use the assembly in my apps that are running .NET 4.5 will the assembly be treated as if it is running in .NET 4.5 instead of .NET 3.5? I have a WinForms app and a WebForms app both in .NET 4.5. If there are changes in behavior between .NET 3.5 and .NET 4.5, with the assembly return the 4.5 results?
Usually .Net frameworks are backward-compatible, so executing an assembly developed in .Net 3.5 shouldn't be a problem on 4.5.
You should see: Version Compatibility in the .NET Framework
The .NET Framework 4.5 is backward-compatible with applications that
were built with the .NET Framework versions 1.1, 2.0, 3.0, 3.5, and 4.
In other words, applications and components built with previous
versions of the .NET Framework will work on the .NET Framework 4.5.
But there could be problems as well like the one mentioned in the article :
However, in practice, this compatibility can be broken by seemingly
inconsequential changes in the .NET Framework and changes in
programming techniques. For example, performance improvements in the
.NET Framework 4 can expose a race condition that did not occur on
earlier versions. Similarly, using a hard-coded path to .NET Framework
assemblies, performing an equality comparison with a particular
version of the .NET Framework, and getting the value of a private
field by using reflection are not backward-compatible practices. In
addition, each version of the .NET Framework includes bug fixes and
security-related changes that can affect the compatibility of some
applications and components.
The best way for you would be make sure your test cases pass after including dll from 3.5.
I am in the process of testing a program (class library). The class library (dll) is testing on various systems: .NET Frameworks 3.0, 3.5 and 4.0. Is it possible to test it on .NET 3.0 and 3.5 without having to upgrade the .NET version?
No you can not do that, but its the other way around, you can test 3.5 dll on .Net framework 4.0. An assembly compiled with .NET 4.0 can be loaded only by the CLR 4.0
The only choices for the application pools are .net 2.0 or 4.0, but my machine is running on 3.5.
I am currently getting a
system.platformnotsupportedexeception
in an app that i built, and i think it might be related to this issue.
Keep in mind, there is no 3.5 version of the .NET runtime - only a 3.5 version of the .NET Framework. The CLR itself is either 2.0 or 4.0. Why they have weird versioning is beyond me (I guess there were no runtime modifications to support the 3.5 framework), but the framework versions are different than the runtime versions.
.NET 3.5 has the same base runtime as .NET 2.0. So in your case, selecting 2.0 is correct.
See this similar question.
My colleagues and I have some misunderstandings about the .NET runtime. I've written a WPF application (targeted for 3.5) that randomly crashes, and in the event log, we see .NET Runtime 2.0 Error Reporting as the source.
Just to confirm:
3.5 still runs on the .NET 2.0 Runtime (i.e., it's an extension of it), so an application targeting 3.5 will still show .NET Runtime 2.0 as it's error source.
When installing .NET 3.5 Framework, there's no way to not install .NET 2.0 along with it.
Am I right?
You are correct. There are, currently, 4 .NET runtimes (though the last is in beta).
1.0 Runtime, which was very buggy
1.1 Runtime
2.0 Runtime, which is used for .NET 2.0, 3.0, 3.5, and 3.5sp1, as well as Silverlight
4.0 Runtime - In Beta2, and soon to be released with VS 2010 and will be used by .NET 4.0
There is no way to install .NET 3.5 without the 2.0 runtime, since it uses that runtime, and is based on it.
You are correct on both points.
Yes, you are right. The .NET 3.5 Framework runs on .NET 2.0 CLR. Essentially the change is new assemblies (and new versions of .NET 2.0 assemblies) and new compilers.