Start Microsoft Visual Studio 2015.

Navigate to File | New | Project menu or press Ctrl + Shift + N.

At the top of the New Project dialog box, choose .NET Framework 4.6.1 (or later). From the Installed Templates list on the left, choose Visual C#. In the list at the center, choose Console Application. Enter the name Ch01_MyFirstApp, set the location to C:\Code, enter Chapter01 as the solution name, and click on OK or press Enter:

In the code editor, inside the Main method, press Enter to insert a new line between the innermost braces { }, and then type the letters sy, as you can see in the following screenshot:

Note that IntelliSense shows a list of keywords, namespaces, and types that contain the letters sy, and highlights the first one that starts with sy, which happens to be the namespace that we want—System.

Type a dot (also known as decimal point or full stop). IntelliSense automatically completes the word System for you, enters the dot, and displays a list of types and namespaces, such as AccessViolationException and Action, in the System namespace, as shown in the following screenshot:

Type the letters con and IntelliSense shows a list of matching types and namespaces:

Press the down arrow on your keyboard to highlight Console, and then type a dot.

IntelliSense shows a list of the members of the Console class:

Type the letters wr. IntelliSense shows two matching members containing these letters:

Use the down arrow to highlight WriteLine and then type an open parenthesis (.

IntelliSense autocompletes WriteLine and enters a pair of parentheses.

You will also see a tooltip telling you that the WriteLine method has 19 variations:

Type a double quote ("). IntelliSense enters a pair of double quotes for you and leaves the keyboard cursor in between them.

Type the text Hello C#!, as shown in the following screenshot:

The red squiggle at the end of the line indicates an error, because every C# statement must end in a semicolon. Move the cursor to the end of the line by pressing End, and type a semicolon to fix the error.

From the Debug menu, choose Start Without Debugging or press Ctrl + F5. Your completed application runs in a console window and closes when you press any key:

To save space and to make the output clearer, I will usually not include screenshots of output from console applications as I did previously. Instead, I will show the output like this:

Hello C#!

Let's make two deliberate errors.

Change the M of the Main method to the lowercase letter m.

Delete the e at the end of the method name WriteLine.

On the Build menu, choose Build Ch01_MyFirstApp or press Shift + F6.

After a few seconds, the status bar tells us that the build failed and the error list is activated. You can also view the error list by pressing Ctrl + W, E:

The Error List can be filtered to show Errors, Warnings, and informational Messages by clicking on the toggle buttons at the top of the window.

If an error shows the line number, for example Line 13 in the preceding screenshot, then you can double-click on the error to jump to the line causing the problem.

If it's a more general error, such as the missing Main method, the compiler can't tell you the line number. You might want a method named main as well as a method named Main (remember that C# is case sensitive so you're allowed to do that).

Fix the two (as shown in the preceding screenshot) errors before you continue. Note that the error list updates to show no errors.

Although Visual Studio has always had an Immediate window with limited REPL (read-eval-print loop) support, Visual Studio 2015 with Update 1 includes an enhanced window with full IntelliSense and color syntax code, named C# Interactive.

On the View menu, choose Other Windows, and then C# Interactive.

We will write some interactive code to download the About page from Microsoft's public website.

At the C# Interactive prompt, we will enter commands to do the following:

Type each of the following commands after the > prompt and then press Enter:

> #r "System.Net.Http"
> using System.Net.Http;
> var client = new HttpClient();
> client.BaseAddress = new Uri("http://www.microsoft.com/");
> var response = await client.GetAsync("about");
> response.StatusCode
OK
> response.Content.Headers.GetValues("Content-Type")
string[1] { "text/html" }
> await response.Content.ReadAsStringAsync()
"<!DOCTYPE html ><html xmlns:mscom=\"http://schemas.microsoft.com/CMSvNext\" xmlns:md=\"http://schemas.microsoft.com/mscom-data\" lang=\"en\" xmlns=\"http://www.w3.org/1999/xhtml\"><head><meta http-equiv=\"X-UA-Compatible\" content=\"IE=edge\" /><meta charset=\"utf-8\" /><meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\" /><link rel=\"shortcut icon\" href=\"//www.microsoft.com/favicon.ico?v2\" /><script type=\"text/javascript\" src=\"http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.7.2.min.js\">\r\n        // Third party scripts and code linked to or referenced from this website are licensed to you by the parties that own such code, not by Microsoft. See ASP.NET Ajax CDN Terms of Use - http://www.asp.net/ajaxlibrary/CDN.ashx.\r\n    </script><script type=\"text/javascript\" language=\"javascript\">/*<![CDATA[*/if($(document).bind(\"mobileinit\",function(){$.mobile.autoInitializePage=!1}),navigator.userAgent.match(/IEMobile\\/10\\.0/)){var msViewportStyle=document.createElement(\"style ...

Visual Studio has lots of other useful windows, including the following:

If you ever can't see a window you need, go to the View menu to make it reappear or learn its keyboard shortcut, as shown here: