What is the difference between PCL and .net standard ?

Hello Rahul,

.NET DLLs are formatted according to ECMA-335 (Better known as the Common Language Infrastructure). This format is true across all platforms we call .NET; Full Framework, Core, Xamarin, Mono, Silverlight, etc.

The reason you couldn't use a DLL compiled against one platform with another was that the format didn't specify APIs (generally speaking). So while they could all read the DLL you'd run into issues of class XYZ being in namespace A.B.C on one platform and in namespace D.E.F on another, if it existed at all.

PCLs "solved" this by doing two things:

They used Type Forwarding so that even though you wrote your code expecting class XYZ in namespace A.B.C, it could be found on platforms that had it elsewhere.

It limited what APIs you could use to the lowest common set shared by all the platforms you wanted.

Taking a PCL and converting it to a .NET Standard project is not a recompile because of output format but because of the meta data included (Type Forwarding particularly).

So, I think that essentially .NET Standard libraries are no different than PCL libraries except for the fact that they put a layer over the top of a different standardized set of APIs, and those APIs may implement different pointers (Type forwarding).

.NET Core is of course a runtime environment, but I think that it is just very closely aligned with .NET Standard. I don't think that it has any special relationship to it other than the fact that it implements the .NET Standard APIs.

In my mind, it is generally better to target a .NET Standard Class library because this will be compatible across multiple platforms. If you target .NET Core, this assembly type cannot be referenced in UWP for example. You will see this:Unable to add a reference to project 'ClassLibrary1' message

However, if you are working in a pure .NET Core environment, you may find that there are APIs available that are specific to the .NET Core runtime environment, and therefore it will be necessary to target .NET Core directly.

5 Replies

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Jefferson S. Motta6y ago
.Net Standard is a wildcard, you can make DLLs with Net Standard 2.0 that works both with Net Core 2.x and .Net Framework 4.x.

With Net Core 3.x you need to use .NET Standard (last version) both works with c# 8.0 while Net Standard 2.x works with C# 7.3.
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Ashutosh Gupta6y ago
for more details
https://stackoverflow.com/questions/39050911/net-standard-net-core-pcl
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Rajanikant Hawaldar6y ago
Hello Rahul,
.NET DLLs are formatted according to ECMA-335 (Better known as the Common Language Infrastructure). This format is true across all platforms we call .NET; Full Framework, Core, Xamarin, Mono, Silverlight, etc.
The reason you couldn't use a DLL compiled against one platform with another was that the format didn't specify APIs (generally speaking). So while they could all read the DLL you'd run into issues of class XYZ being in namespace A.B.C on one platform and in namespace D.E.F on another, if it existed at all.
PCLs "solved" this by doing two things:
They used Type Forwarding so that even though you wrote your code expecting class XYZ in namespace A.B.C, it could be found on platforms that had it elsewhere.
It limited what APIs you could use to the lowest common set shared by all the platforms you wanted.
Taking a PCL and converting it to a .NET Standard project is not a recompile because of output format but because of the meta data included (Type Forwarding particularly).

So, I think that essentially .NET Standard libraries are no different than PCL libraries except for the fact that they put a layer over the top of a different standardized set of APIs, and those APIs may implement different pointers (Type forwarding).
.NET Core is of course a runtime environment, but I think that it is just very closely aligned with .NET Standard. I don't think that it has any special relationship to it other than the fact that it implements the .NET Standard APIs.
In my mind, it is generally better to target a .NET Standard Class library because this will be compatible across multiple platforms. If you target .NET Core, this assembly type cannot be referenced in UWP for example. You will see this:Unable to add a reference to project 'ClassLibrary1' message
However, if you are working in a pure .NET Core environment, you may find that there are APIs available that are specific to the .NET Core runtime environment, and therefore it will be necessary to target .NET Core directly.
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Rahul Kumar6y ago
thank you #mathews for your response but what about .net standard
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Jaish Mathews6y ago
.NET has different development platforms like .NET Framework, Core, Xamarin, Mono, Silverlight, etc.

If you compile a DLL in one of the above platforms, it may not compatible with other platforms. PCL is solving this issue. So if you are targetting only one of the .NET platform, PCL not matters you. Please Ref. this link, https://stackoverflow.com/questions/39050911/net-standard-net-core-pcl , for details .
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