In Visual Studio, go to the Tools menu and choose Extensions and Updates….

On the left-hand side of the dialog, click on Online. In the Search Visual Studio Gallery box, type portability and press Enter.

Click on the .NET Portability Analyzer entry and then click on the Download button. Once the extension is installed, restart Visual Studio:

In Visual Studio, go to the Tools menu and choose Options.

In the Options dialog box, scroll down through the left-hand side list and choose .NET Portability Analyzer. In the Target Platforms section, deselect everything except for the following:

In Visual Studio, open the previous solution, named Chapter01. In the Solution Explorer window, right-click on the project named Ch01_MyFirstApp (not the solution), choose Analyze, and then choose Analyze Assembly Portability.

After a few seconds, a report will display in the main area.

Note that the Console class in the System namespace and its WriteLine method are supported by the following:

However, it is not supported by .NET Native 1.0:

Press Ctrl + W, E to view the error list, which has also been populated. As we saw earlier, double-clicking on an error will jump the code editor to the line that could cause an issue:

I used the .NET Portability Analyzer while writing all the code in this book to ensure that, whenever possible, I can show you code that will work cross-platform using the .NET Core 1.0. If there are useful features that aren't cross-platform yet, then I will point that out in the text. Hopefully, they will be implemented in .NET Core in future versions.

There are two sets of command-line tools that you can use to manage the .NET Core:

First, we must install the .NET Command Line Tools (CLI).

Start Microsoft Edge and go to the https://github.com/dotnet/cli.

Scroll down the page to find the Installers section and click on the link to download the MSI file for Windows. Open the file and install.

Start the Developer Command Prompt for VS2015. At the prompt, enter the following command:

dotnet

You should see the following output:

Enter the following at the prompt to create a new directory, change to it, create a new console application in the directory, and then list the files it created:

cd C:\Code\Chapter01
mkdir Ch01_MySecondApp
cd Ch01_MySecondApp
dotnet new
dir

You should see that the dotnet tool has created three new files for you: NuGet.Config, Program.cs, and project.json.

At the prompt, enter the following to start Notepad for editing the Program class:

notepad Program.cs

In Notepad, modify the WriteLine statement as follows:

Console.WriteLine("Hello C#, Welcome .NET Core!");

Save changes and exit Notepad.

At the prompt, enter the following commands:

dotnet restore
dotnet run

After a few seconds, all the dependency packages will be downloaded and your application will run, showing the following output:

To compile the source code into an assembly containing IL code, enter the following command:

dotnet build

The output in the Command Prompt window should look like this:

Enter the following commands to change to a subdirectory, list the files in it, and execute the compiled console application:

cd bin\Debug\dnxcore50
dir
Ch01_MySecondApp

Start Visual Studio 2015 and open the Chapter01 solution.

In Visual Studio, navigate to File | Add | New Project.

In the Add New Project dialog box, in the Installed Templates list on the left-hand side, choose Visual C#. In the list at the center, choose Console Application (Package). Enter the name Ch01_DotNetCore, and click on OK or press Enter:

In the Solution Explorer window, right-click on the solution named Chapter01 and choose Properties.

Set the Startup Project to Current selection and click on OK.

Inside the Main method of the Program class, enter the following statements:

Console.WriteLine("Welcome, .NET Core!");
Console.ReadLine();

As you type code, you will notice that Visual Studio shows you which types and methods might not be available when targeting .NET Core. For example, the BufferHeight property is available when targeting the .NET Framework but not the .NET Core, as shown in the following screenshot as DNX 4.5.1 and DNX Core 5.0 respectively:

You can tell the compiler to include statements available only when .NET Framework is available by using conditional compilation symbols, as follows:

#if DNX451
    Console.BufferHeight = 300;
#elseif DNXCORE50
    // some alternative for .NET Core
#endif

In the Solution Explorer window, double-click on Properties for the Ch01_DotNetCore project.

In the Properties window, click on the Debug tab, select the Use Specific Runtime checkbox, and select the latest version of the .NET Core platform for the x64 CPU architecture, as shown in the following screenshot:

In the Visual Studio Debug menu, choose Start or press F5.

Note that the Command Prompt window shows that the console application is running the dnx-coreclr-win-x64.1.0.0-rc1-update1 runtime: