What is managed/unmanaged code in C#?

Question

I am using Assembly.GetEntryAssembly()... in my C# code to get the version of the application. It runs fine but when I try it in NUnit it returns NULL. In the MSDN it states that it can return NULL when called from unmanaged code.

What is managed or unmanaged code? I do not get it.

Answer 1

Here is some text from MSDN about unmanaged code.

Some library code needs to call into unmanaged code (for example, native code APIs, such as Win32). Because this means going outside the security perimeter for managed code, due caution is required.

Here is some other complimentary explication about Managed code:

• Code that is executed by the CLR.
• Code that targets the common language runtime, the foundation of the .NET Framework, is known as managed code.
• Managed code supplies the metadata necessary for the CLR to provide services such as memory management, cross-language integration, code access security, and automatic lifetime control of objects. All code based on IL executes as managed code.
• Code that executes under the CLI execution environment.

For your problem:

I think it's because NUnit execute your code for UnitTesting and might have some part of it that is unmanaged. But I am not sure about it, so do not take this for gold. I am sure someone will be able to give you more information about it. Hope it helps!

Answer 2

Basically unmanaged code is code which does not run under the .NET CLR (aka not VB.NET, C#, etc.). My guess is that NUnit has a runner/wrapper which is not .NET code (aka C++).

Answer 3

This is a good article about the subject.

Crib sheet:

Managed code is not compiled to machine code but to an intermediate language which is interpreted and executed by some service on a machine and is therefore operating within a (hopefully!) secure framework which handles dangerous things like memory and threads for you. In modern usage this frequently means .NET but does not have to.

Unmanaged code is compiled to machine code and therefore executed by the OS directly. It therefore has the ability to do damaging/powerful things Managed code does not. This is how everything used to work, so typically it's associated with old stuff like .dlls

Native code is often synonymous with Unmanaged, but is not identical.

Answer 4

NUnit loads the unit tests in a seperate AppDomain, and I assume the entry point is not being called (probably not needed), hence the entry assembly is null.

Answer 5

I as few words as possible. Managed code = .NET programs. Unmanaged code = "normal" programs.

Answer 6

Managed code runs inside the environment of CLR i.e. .NET runtime.In short all IL are managed code.But if you are using some third party software example VB6 or VC++ component they are unmanaged code as .NET runtime (CLR) does not have control over the source code execution of the language.