In the previous lesson, we introduced data types that are usually referred to as primitive. Each of these data types is used to create an object that can hold a single value, such as the number of bedrooms of a house, the type of house, etc. Here are examples of such variables:

using namespace System; int main() { __wchar_t TypeOfHome; int Bedrooms; Byte Stories; double Bathrooms; int YearBuilt; double Value; return 0; }

Notice that, in this example, some or all of the variables could be used to create a single object.

1. To start a new program, launch Microsoft Visual C++ 2005
2. On the main menu, click File -> New -> Project...
3. On the left side, make sure that Visual C++ is selected. In the Templates list, click CLR Empty Project
4. In the Name box, replace the string with RealEstate4 and click OK
5. To create a source file, on the main menu, click Project -> Add New Item...
6. In the Templates list, click Source File (.cpp)
7. In the New box, type Exercise and click Add
8. In the empty file, type:
    

   using namespace System; int main() { Console::WriteLine("=//= Altair Realty =//="); Console::WriteLine("-=- Properties Inventory -=-"); return 0; }

9. To execute the application, on the main menu, click Debug -> Start Without Debugging
10. Click Yes

The C++ language allows you to use one, or a group of more than one, type of values to create what would be referred to as a composite type. This type is created as a class. As introduced in Lesson 1, to create a class, start with either the struct or the class keyword, followed by a name and ending with a semi-colon. The name of the class follows the same rules we have been applying to the variables so far. Here is an example:

struct House;

Or

class House;

We we will start the names of our classes with C:

struct CHouse;

Or

class CHouse;

After creating a CHouse class like this, it doesn't (yet) have any functionality. You have simply indicated that you want a data type that is itself one or a group of values. To create it, you list the parts of a class between an opening curly bracket "{" and a closing curly bracket "}". Everything between these brackets is part of the class and such a section is referred to as the body of the class. It would be created as follows:

struct CHouse{ };

Or

class CHouse{ };

In the body of the class, you can list the items that compose it. Each item is called a member of the class. Each item is identified by its type and a name. For example, if you want to create a CHouse class that is simply known for its value, you can define a member value of double type. Such a class would look like this:

struct CHouse{ double Value; };

Or

class CHouse{ double Value; };

Most objects are made of various parts. Listing all parts on a single line could be cumbersome. Therefore, you can span the body of a class on various lines. An example would be:

struct CHouse {
// Body of the class
};

or

struc CHouse
{
// Body of the class
};

Or

class CHouse {
// Body of the class
};

or

class CHouse
{
// Body of the class
};

In the body of the class, you can then list its members. Each member is created as a variable, declaring it using any of the techniques we used in the previous lesson. Here are examples:

struct CHouse { __wchar_t TypeOfHome; int Bedrooms; Byte Stories; double Bathrooms; int YearBuilt; double Value; };

class CHouse { __wchar_t TypeOfHome; int Bedrooms; Byte Stories; double Bathrooms; int YearBuilt; double Value; };

If two variables are of the same type, you can declare them with one data type as done for variable declarations in the previous lesson. Here is an example:

struct CHouse
{
	__wchar_t TypeOfHome;
	int Bedrooms, YearBuilt;
	Byte Stories;
	double Bathrooms, Value;
};

class CHouse
{
	__wchar_t TypeOfHome;
	int Bedrooms, YearBuilt;
	Byte Stories;
	double Bathrooms, Value;
};

To indicate that a member variable belongs to the class, another way you can declare it is by preceding its name with the name of the class followed by the :: operator. Here are example:

struct CHouse
{
	__wchar_t CHouse::TypeOfHome;
	int CHouse::Bedrooms;
	Byte CHouse::Stories;
	double CHouse::Bathrooms;
	int CHouse::YearBuilt;
	double CHouse::Value;
};

class CHouse
{
	__wchar_t TypeOfHome;
	int CHouse::Bedrooms, YearBuilt;
	Byte Stories;
	double Bathrooms, CHouse::Value;
};

1. 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 and click Add
4. In the empty file, type the following:
    

   #pragma once class CHouse { long PropertyNumber; __wchar_t PropertyType; unsigned Stories; unsigned Bedrooms; float Bathrooms; unsigned YearBuilt; double PropertyValue; };

5. Save the file