Visual Studio IDE

So far we have examined how to compile and run C# programs using the Windows console (Command Prompt). Of course, there is an easier way to do it – by using an integrated development environment, which will execute all the commands we have used so far. Let’s take a look at how to work with development environments (IDE) and how they will make our job easier.

Integrated Development Environments

In the previous examples, we examined how to compile and run a program consisting of a single file. Usually programs are made of many files, sometimes even tens of thousands. Writing in a text editor, compiling and executing a single file program from the command prompt are simple, but to do all this for a big project can prove to be a very complex and time-consuming endeavor. There is a single tool that reduces the complexity, makes writing, compiling and executing software applications easier – the so called Integrated Development Environment (IDE). Development environments usually offer many additions to the main development functions such as debugging, unit testing, checking for common errors, access to a repository and others.

What Is Visual Studio?

Visual Studio is a powerful integrated environment (IDE) for developing software applications for Windows and the .NET Framework platform. Visual Studio (VS) supports different programming languages (for example C#, VB.NET and C++) and different software development technologies (Win32, COM, ASP.NET, ADO.NET Entity Framework, Windows Forms, WPF, Silverlight, Windows Store apps and many more Windows and .NET technologies). It offers a powerful integrated environment for writing code, compiling, executing, debugging and testing applications, designing user interface (forms, dialogs, web pages, visual controls and others), data and class modeling, running tests and hundreds of other functions.

IDE means “integrated development environment” – a tool where you write code, compile it, run it, test it, debug it, etc. and everything is integrated into a single place. Visual Studio is typical example of development IDE.

.NET Framework 4.5 comes with Visual Studio 2012 (VS 2012). This is the latest version of Visual Studio as of March 2013. It is designed for C# 5, .NET 4.5 and Windows 8 development.

VS 2012 is a commercial product but has a free version called Visual Studio Express 2012, which can be downloaded for free from the Microsoft website at http://microsoft.com/visualstudio/downloads.

Visual Studio 2012 Express has several editions (for Desktop, for Web, for Windows 8 and others). If you want to write C# code following the content of this book, you may use Visual Studio 2012 Express for Desktop or check whether you have a free license of the full Visual Studio from your University or organization. Many academic institutions (like Sofia University and Telerik Software Academy) provide free Microsoft DreamSpark accounts to their students to get licensed Windows, Visual Studio, SQL Server and other development tools. If you are student, ask your university administration about the DreamSpark program. Most universities worldwide are members of this program.

In this book we will take a look at only the most important functions of VS Express 2012 – the ones related to coding. These are the functions for creating, editing, compiling, executing and debugging programs.

Note that older Visual Studio versions such as VS 2010 and VS 2008 can also be used for the examples in this book but their user interface might look slightly different. Our examples are based on VS 2012 on Windows 8.

Before we continue with an example, let’s take a more detailed look of the structure of Visual Studio 2012’s visual interface. Windows are the main part of it. Each of them has a different function tied to the development of applications. Let’s see how Visual Studio 2012 looks after the default installation and configuration:

Visual Studio has several windows that we will explore (see the figures above and below):

-              Start Page – from the start page we can easily open any of our latest projects or start a new one, to create our first C# program or to get help how to use C#.

-              Code Editor – keeps the program’s source code and allows opening and editing multiple files.

-              Error List – it shows the errors in the program we develop (if any). We learn how to use this window later when we compile C# programs in Visual Studio.

-              Solution Explorer – when no project is loaded, this window is empty, but it will become a part of our lives as C# programmers. It will show the structure of our project – all the files it contains, regardless if they are C# code, images or some other type of code or resources.

-              Properties – holds a list of the current object’s properties. Properties are used mainly in the component-based programming, e.g. when we develop WPF, Windows Store or ASP.NET Web Forms application.

There are many other windows with auxiliary functionality in Visual Studio but we will not review them at this time.

Creating a New C# Project

Before doing anything else in Visual Studio, we must create a new project or load an existing one. The project groups many files, designed to implement a software application or system, in a logical manner. It is recommended that we create a separate project for each new program.

We can create a project in Visual Studio by following these steps:

-      File -> New Project …

-      The “New Project” dialog appears and lists all the different types of projects we can create. We can choose a project type (e.g. Console Application or WPF Application), programming language (e.g. C# or VB.NET) and .NET Framework version (e.g. .NET Framework 4.5) and give a name to our project (in our case “IntroToCSharp”):

-      We choose Console Application. Console applications are programs, which use the console as a default input and output. Data is entered with the keyboard and when a result needs to be printed it appears on the console (as text on the screen in the program window). Aside from console applications, we can create applications with a graphical user interface (e.g. Windows Forms or WPF), Web applications, web services, mobile applications, Windows Store apps, database projects and others.

-      In the field "Name" we enter the name of the project. In our case we choose the name IntroToCSharp.

-      We press the [OK] button.

The newly created project is now shown in the Solution Explorer. Also, our first file, containing the program code, is automatically added. It is named Program.cs. It is very important to give meaningful names to our files, classes, methods and other elements of the program, so that we can easily find them and navigate the code. A meaningful name means a name that answers the question “what is the intent of this file / class / method / variable?” and helps developers to understand how the code works. Don’t use Problem3 for a name, even if you are solving the problem 3 from the exercises. Name your project / class by its purpose. If your project is well named, after few months or a year you will be able to explain what it is intended to do without opening it and looking inside. Problem3 says nothing about what this project actually does.

In order to rename the Program.cs file, we right click on it in the Solution Explorer and select "Rename". We can name the main file of our C# program HelloCSharp.cs. Renaming a file can also be done with the [F2] key when the file is selected in the Solution Explorer:

A dialog window appears asking us if we want to rename class name as well as the file name. We select "Yes".

After we complete all these steps we have our first console application named IntroToCSharp and containing a single class HelloCSharp (stored in the file HelloCSharp.cs):

All we have to do is add code to the Main() method. By default, the HelloCSharp.cs code should be loaded and ready for editing. If it is not, we double click on the HelloCSharp.cs file in the Solution Explorer to load it. We enter the following source code:

Compiling the Source Code

The compiling process in Visual Studio includes several steps:

-      Syntax error check;

-      A check for other errors, like missing libraries;

-      Converting the C# code into an executable file (a .NET assembly). For console applications it is an .exe file.

To compile a file in Visual Studio, we press the [F6] key or [Shift+Ctrl+B]. Usually, errors are underlined in red, to attract the programmer’s attention, while we are still writing or when compiling, at the latest. They are listed in the "Error List" window if it is visible (if it is not, we can show it from the "View" menu of Visual Studio).

If our project has at least one error, it will be marked with a small red "x" in the "Error List" window. Short info about the problem is displayed for each error – filename, line number and project name. If we double click any of the errors in the "Error List", Visual Studio will automatically take us to the file and line of code where the error has occurred. In the screenshot above the problem is that we have “using Systema;” instead of “using System”.

Starting the Project

To start the project, we press [Ctrl+F5] (holding the [Ctrl] key pressed and at the same time pressing the [F5] key).

The program will start and the result will be displayed on the console, followed by the "Press any key to continue . . ." message:

The last message is not part of the result produced by the program. It is a reminder by Visual Studio that our program has finished its execution and it gives us time to see the result. If we run the program by only pressing [F5], that message will not appear and the result will vanish instantly after appearing because the program will have finished its execution, and the window will be closed. That is why we should always start our console applications by pressing [Ctrl+F5].

Not all project types can be executed. In order to execute a C# project, it needs to have one class with a Main() method declared in the way described earlier in this chapter.

Debugging the Program

When our program contains errors, also known as bugs, we must find and remove them, i.e. we need to debug the program. The debugging process includes:

-      Noticing the problems (bugs);

-      Finding the code causing the problems;

-      Fixing the code so that the program works correctly;

-      Testing to make sure the program works as expected after the changes are made.

The process can be repeated several times until the program starts working correctly. After we have noticed the problem, we need to find the code causing it. Visual Studio can help by allowing us to check step by step whether everything is working as planned.

To stop the execution of the program at designated positions we can place breakpoints. The breakpoint is associated with a line of the program. The program stops its execution on the lines with breakpoints, allowing for the rest of the code to be executed step by step. On each step we can check and even change the values of the current variables.

Debugging is a sort of step by step slow motion execution of the program. It gives us the opportunity to easily understand the details of the code and see where exactly and why the errors have occurred.

Let’s create an intentional error in our program, to illustrate how to use breakpoints. We will add a line to the program, which will create an exception during the execution (we will take a detailed look at exceptions in the "Exception Handling" chapter).

For now let’s edit our program in the following way:

HelloCSharp.cs

class HelloCSharp {       static void Main()       {             throw new System.NotImplementedException(                   "Intended exception.");             System.Console.WriteLine("Hello C#!");       } }

When we start the program again with [Ctrl+F5] we will get an error and it will be printed on the console:

Let’s see how breakpoints will help us find the problem. We move the cursor to the line with the opening bracket of the Main() method and press [F9] (by doing so we place a breakpoint on that line). A red dot appears, indicating that the program will stop there if it is executed in debug mode:

Now we must start the program in debug mode. We select Debug -> Start Debugging or press [F5]. The program will start and immediately stop at the first breakpoint it encounters. The line will be colored in yellow and we can execute the program step by step. With the [F10] key we move to the next line.

When we are on a given line and it is colored in yellow, the code on that line is not executed yet. It executes once we have passed that line. In this case we have not received the error yet despite the fact that we are on the line we added and should cause it:

We press [F10] one more time to execute the current line. This time Visual Studio displays a window specifying the line, where the error occurred as well as some additional details about it:

Once we know where exactly the problem in the program is, we can easily correct it. To do so, first, we need to stop the execution of the program before it is finished. We select Debug –> Stop Debugging or press [Shift+F5]. After that we delete the problem line and start the program in normal mode (without debugging) by pressing) [Ctrl+F5].