We mentioned earlier that, after creating the instructions in a text file, you could submit them to the compiler. This is also referred to as compiling or executing the project. To do this simply, on the main menu of Microsoft Visual C++, you can click Debug -> Start Without Debugging. The shortcut is Ctrl + F5. If this is the first time you perform this action or the file had been modified since the last time you did this, you would be asked to save it, which you should do.

When executing the program, it there is no error, it would display its result. If there is at least one error, you would be prompted to correct it.

After viewing the result of a program, to close the DOS window, you can press Enter, and return to MSVC.

Code Comments

In computer programming, a comment is text that the compiler will ignore when reading the contents of the source code. For this reason, you can write a comment to your liking. In order for the compiler to skip the section that contains a comment, this section must be delimited appropriately. The C++ language has two types of comment.

To write a comment on a line, start the line with //. Everything on the right side of // will not be considered by the compiler. Here are two examples:

// Exercise.cpp

int main()
{

// This is the last line of the function
return 0;
}

The // character is used to create a comment on one line. You can use it on different and on as many lines as you want. If you want a comment to cover more than one line, start the section with /* and end it with */. Anything between /* and */ is considered a comment and will not be considered during compilation. Here is an example of such a comment:

// Exercise.cpp

int main()
{
/* Anything on this section
will not be considered by the compiler.
I can write anything I want in it */

return 0;
}

Indentation is another feature that makes your program easy to read. Indentation is a technique of grouping lines of code by category. For example, we saw that the body of a function starts with an opening curly bracket “{“ and ends with a closing curly bracket “}”. To delimit the items that are inside of a function, you should indent them by two empty spaces or one tab. By default, Microsoft Visual Studio sets a Tab press to 4 characters.

Using indentation, the program could be written:

// Exercise.cpp

int main()
{
	/* Anything on this section
	   will not be considered by the compiler.
	   I can write anything I want in it */

	return 0;
}

Indentation should be incremental. That is, when a line of code appears to be a child of the previous line, the new line should be indented.

An escape sequence is a character that holds a special meaning to the compiler such as switching to the next line or adding a tab indentation. Although an escape sequence is a character by definition, it is created using the backslash “\” followed by a specific character. For example, the escape sequence \n asks the compiler to add or create a new line, also referred to as Carriage Return or “Carriage Return – Line Feed”.

To use an escape sequence by itself, you can include between double quotes: “\n”. Because escape sequences are specially recognized by the compiler, they can be included in a string. Since the compiler will still read a string, if it finds an escape sequence, it acts accordingly. Here is a list of escape sequences and their meanings:

A class is a technique of creating one or a group of objects to be considered as an entity. To create a class, you must type class or struct, followed by a name, followed by an opening curly bracket "{", a closing curly bracket "}", and a semi-colon. Here is an example: struct house { }; One of the types of things you can include in a class is a function. To do this, you write the function exactly as we saw earlier. Here is an example:

struct house
{
	int protect()
	{
		return 0;
	}
};

int main()
{
	return 0;
}

When a function is created outside of any class, it is called a function. When a function is created inside of a class, it is called a method. For the rest of this ebook, we will use the word "method" to indicate that the function belongs to a class.

You can include or create as many methods as you judge necessary in the body of a class. After creating a class, in order to use it, you must first create an "object" from it. This means that you must "declare" the class. To do this, for example in the body of main(), type the name of the class followed by another name that represents the object. Here is an example:

struct house
{
	int protect()
	{
		return 0;
	}
};

int main()
{
	house home;

	return 0;
}

After this declaration, the word home is called an object. After creating the object, such as home above, to access one of its method, type the name of the object, followed by a period, followed by the name of the method, its parentheses, and a semi-colon. Here is an example:

struct house
{
	int protect()
	{
		return 0;
	}
};

int main()
{
	house home;

	home.protect();

	return 0;
}

You don't always have to primarily create an object before using a class. To apply this exception, the name of a method that belongs to a class must be preceded with static. Here is an example:

struct house
{
	static int protect()
	{
		return 0;
	}
};

int main()
{
	return 0;
}

When a method has been created with the static keyword, it is called a static method. To access it outside of the class, for example to access the above protect from main(), you can type the name of the class, followed by ::, followed by the name of the method, its parentheses, and a semi-colon. Here is an example:

struct house
{
	static int protect()
	{
		return 0;
	}
};

int main()
{
	house::protect();

	return 0;
}

1. To create a class, change the file as follows:

   // RealEstate1.cpp : main project file.
   
   #include "stdafx.h"
   
   using namespace System;
   
   class CProperty
   {
   	int ShowWelcome()
   	{
   		return 0;
   	}
   };
   
   int main(array<System::String ^> ^args)
   {
       Console::WriteLine(L"Hello World");
       return 0;
   }

2. Save the file

C++ is one of those languages that can use different files for a program. The most usual file used in a C++ program is called a source file. It is a file with the .cpp extension. This type of file simply contains code that the compiler would need to know what the program is supposed to do. When using Microsoft Visual C++, you can create a source file at any time, whether you are working on a project or not. You can even create a source file to use in another project.

To create a source file in Microsoft Visual C++ 2008:

• If you are not working on a particular project, for example if you have just opened Microsoft Visual C++, on the menu, you can click File -> New -> File... In the New File dialog box, click C++ File (.cpp) in the Templates list and click Open. A file with the default name of Source1.cpp would display. You can then enter your code. To save the file, on the main menu, you can click File -> Save Source1.cpp. Save the file in any directory of your choice and give it a valid name
• If you are working on a project already, on the menu, you can click Project -> Add New Item... In the Add New Item dialog box, click C++ File (.cpp) in the Templates list. Give the file a name in the Name edit box and click Add. A new empty file would be added to the current project. You can then enter your code

If you already have a source file somewhere on a drive or on the network and you want to use that file in your project, on the main menu, you can click Project -> Add Existing Item... In the Add Existing Item dialog box, in the Look In combo box, display the folder that contains the file, locate the file you want to use, select it, and click Add.

1. To create a source file, on the main menu, click Project -> Add New Item...
2. In the Templates list, click Source File (.cpp)
3. In the New box, type Property
    
   
4. Click Add

C++ is one of the few languages that have or use the concept of header files. A header file is one that contains code that source files or other header files of a project use. In the strict sense, there is no rule as to what type of code you can put in the header file. Traditionally, programmers put in a header file the items that are not defined. For example, you can put the "skeletons" of your functions or the "skeletons" of your classes. One reason you would do this is to only show to other people what your functions or classes look like, not how they behave. In some cases, if you are creating a library (a DLL) that you want to sell or distribute to other programmers, a header file allows you to show these skeletons. You can then use a source file to define these skeletons. When you sell or distribute such a library, you don't include the source file. You distribute only the header file and the library itself. Since your customers or your audience cannot "read" what is in a library, they cannot access your hard work source file.

Because C# and Visual Basic don't use header files in the strict sense, some programmers don't encourage you to create them. In this ebook, we will adhere to C++ techniques. Therefore, we will create header files whenever we "feel like it".

A header file is a C++ document with the extension .h and sometimes .hpp. As mentioned for source files, you can create a header file at any time, whether a project is opened or not. In Microsoft Visual C++ 2008, to create a header file:

• If you are not working on a project, on the menu, you can click File -> New -> File... In the New File dialog box, click Header File (.h) in the Templates list and press Enter. A file with the default name of Header1.h would open. After entering your code, to save the file, on the main menu, you can click File -> Save Header1.h. Save the file in any directory of your choice and give it a valid name
• If you are working on a project already, on the menu, you can click Project -> Add New Item... In the Add New Item dialog box, click Header File (.h) in the Templates list. In the Name edit box, enter a valid name for the file and press Enter. You can then enter your code

If a header file exists somewhere in your computer in a network drive and you want to use it in your project, on the main menu, you can click Project -> Add Existing Item... In the Look In combo box of the Add Existing Item dialog box, display the folder that contains the file. Select the desired file and click Add.

If the foundation of a class had been specified in a header file and you want o use such a file in your source file, you must include it using the formula:

#include "FileName.h"

When we do more detailed studies of classes, we will see how the header and source files are used in these scenarios.

1. To create a header file, on the main menu, click Project -> Add New Item...
2. In the Templates list, click Header File (.h)
3. In the New box, type Property
    
   
4. Click Add
5. In the empty file, type the following:

   class CProperty
   {
   	int ShowWelcome();
   };

6. Click the Property.cpp tab and type the following in its file

   #include "stdafx.h"
   #include "Property.h"
   
   int CProperty::ShowWelcome()
   {
   	return 0;
   }

7. Click the RealEstate1.cpp tab and change it to have the following contents:

   // RealEstate1.cpp : main project file.
   
   #include "stdafx.h"
   #include "Property.h"
   
   using namespace System;
   
   int main(array<System::String ^> ^args)
   {
       Console::WriteLine(L"Hello World");
       return 0;
   }

8. To save all files, on the main menu, click File -> Save All.
   Except when creating the files, everything we wrote was for experimental purposes. Don't be concerned with any section you may not understand. We will come back to everything as it becomes necessary

After creating the header and source files, when you execute the project, the compiler will find and "synchronize" them to create an executable. The result that the compiler produces by unifying these and other necessary files of a project is called an assembly. If you are creating projects that you intend to use solely in C++, you usually don't care about this and it is done transparently.

We mentioned that the most fundamental function used in C++ was main(). The functionality of a program starts with main() and ends in main(). For this reason, main() is considered the entry and the exit point. We also mentioned that, with Microsoft Visual C++, you could create libraries that you can then sell or distribute to other programmers. One of the particularities of a library, as compared to the traditional projects we will mostly create, is that a library doesn't have an entry point: it may contain just functions and/or classes. You create it with the necessary header and source files, but you don't need to include an entry point. After creating or adding the necessary files to the project, you can then compile it. In this case, the compiler would also create an assembly.

When an assembly has an entry point, which is the case for a regular executable, it is called an application.

One of the most useful aspects of a programming studio such as Microsoft Visual Studio (or Borland Developer Studio) is that it allows you to create objects, such as classes, using a language of your choice, but that other programming environments or languages, can utilize. The programmers of these languages don't need to know the original language. Based on this, you can create a class in C++ and use that class in Visual Basic, when indeed these are two completely different languages. In order to make this happen, as you may suspect, there are rules you must follow. If you create a class in an assembly, by default, that class class can be used only by the other files or objects of the same project. Such a class is referred to as private. If you want, in your project, you can create a class that can be used in another project, whether the project is in C++, in C#, or in Visual Basic. Such a class must be made public. The ability to be public or private for a class is controlled using the public and private keywords.

As seen so far, you can create a class as follows:

class house
{
};

As mentioned already, such a class is considered private. If you want this class to be accessible outside of its assembly, you must make it public. To do this, precede its struct or class keyword with the public keyword. Here is an example:

public class house
{
};

If you don't specify public, the class is considered private. Based on this, the notation:

class house
{
};

is the same as:

private class house
{
};

1. To make the CProperty class public, change the Property.h file as follows:
   

   public class CProperty
   {
   	int ShowWelcome();
   };

2. Save the file

Microsoft Visual Studio provides a more flexible technique of creating a header file combined with a source file. This allows you to get both files with one click. Both files are created from a class. To create the class, on the main menu, you can click Project -> Add Class... In the Templates list of the Add Class dialog box, click C++ Class and click Add. Enter a name if the Class Name text box. By a tradition dating from the previous versions of Microsoft Visual C++, you should start the name of the class with C. If you start the name of the class with C, a header file and a source file without the C would be suggested, which you should accept, and click Finish. To keep this Visual C++ tradition, we will start most names of our classes with C.

1. On the main menu, click Project -> Add Class...
2. In the left frame, expand the Visual C++ node and click C++
3. To create a class, in the Templates list, click C++ Class
    
   
4. Click Add
5. In the Class Name box, type CRealEstateAgent
6. Click Finish.
   Once again, don't mind the skeleton code that was written. The purpose of this exercise was to show you how to create a class

Code of an application is written in plain English and readable to human eyes. For a C++ application, you can use any text editor to write your code but one of Visual Studio's main strengths is the code editor that it has always brought. It is very intuitive.

The Code Editor is a window specially designed for code writing.

Although all languages of the Visual Studio .NET programming environment share the Code Editor, once you have started a type of application, the Code Editor is adapted to the language you are using. Its parser (a program used internally to analyze your code) behaves according to the language you are using. The features and behaviors of the Code Editor are also different, depending on the language.

To display the code editor, if you created an empty project, you can click Project on the main menu and select one of the options that would lead either to a blank text file or a file that contains primary code.

The Code Editor of Visual C++ is divided in 4 sections:

The top section of the Code Editor displays tabs of property pages. Each tab represents a file. To add a new file to the project, on the main menu, you can click

• File -> Add New Item...
• Project -> Add New Item...

Once in the Add New Item dialog box, in the Templates section, click the type of file you want to create, type a name in the Name text box, and press Enter. After the file has been created, it is represented by a tab in the top section of the Code Editor. In the same way, you can add as many files as you judge them necessary. Because there can be different types of files, each has an extension that allows you to know the type of file the tab is holding.

To access one of theses files, you can click its corresponding tab. By default, the tabs display in the order their files were created or added to the project, from left to right. If you don't like that arrangement, click and drag its tab either left or right beyond the next tab.

The top-left section of the Code Editor displays a combo box. If you position the mouse on it, a tool tip that starts with Scopes in would appear. The Scope combo box holds a list of the types as classes and structures that are used in the current project. You can display the list if you click the arrow of the combo box. Each item of the Scope combo box displays the name of its type associated with its parent as implemented in the code. 

The top-right section of the Code Editor displays a combo box named Members. If you position the mouse on it, a tool tip that starts with Functions would appear. The Functions combo box holds a list of the members of a class. The content of the Functions combo box depends on the item that is currently selected in the Scopes combo box. This means that, before accessing the members of a particular class, you must first select that class in the Scopes combo box. Then, when you click the arrow of the Functions combo box, the members of only that class display.

If you select an item from the Functions combo box, the Code Editor jumps to that member in the header file and positions the cursor to the left of the member.

Code is written in a wide area with a white background. This is the area you use the keyboard to insert code with common readable characters. The Code Editor uses some colors to differentiate categories of words or lines of text:

The colors used are highly customizable. To change the colors, on the main menu, you can click Tools -> Options... In the Options dialog box, in the Environment section, click Fonts and Colors. To set the color of a category, in the Display Items section, click the category. In the Item Foreground combo box, select the desired color. If you want the words of the category to have a colored background, click the arrow of the Item Background combo box and select one:

In both cases, the combo boxes display a fixed list of colors. If you want more colors, you can click a Custom button to display the Color dialog box that allows you to "create" a color.

The Solution Explorer is a window that displays the file names and other items used in your project. The items of this window display in a tree. To expand a node, you can click its + button. To collapse it, click its - button. To explore an item, you can double-click it. The result depends on the item you double-clicked.

The Solution Explorer can be used to create and add a new class, a new resource, or a reference to the current project. It can also be used to add a another project to the current project. To perform any of these operations, you can right-click a folder node such as the name of the project, the Source Files, the Header Files, or the Resource Files nodes, position the mouse on Add and select the desired operation:

Remember that you can also perform any of these operations from the Project category of the main menu.

Besides adding new items to the project, you can also use the Solution Explorer to build the project or change its properties. If you add one or more other project(s) to the current one, one of the project must be set as the default. That project would be the first to come up when the user executes the application. By default, the first project created is set as the default. If you have more than one project, to set the default, right-click the name of the desired project in Solution Explorer and click Set As StartUp Project.

The Solution Explorer also you to rename or delete some of the items that belong to your project.

The Class View displays the various classes used by your project, including there ancestry. The items of the Class View an organized as a tree list with the name of the project on top.

The Class View shares some of its functionality with the Solution Explorer. This means that you can use it to build a project, to add new class or a new resource. You can also use it to change the default project if you have more than one.

While the Solution Explorer displays the items that are currently being used by your project, the Class View allows you to explorer the classes used in your applications, including their dependencies. For example, some times you will be using a control of the of the .NET Framework and you may wonder from what class that control is derived. The Class View, rather than the Solution Explorer, can quickly provide this information. To find it out, expand the class by clicking its + button.