### Using the Sample Applications

Sample application files are provided with the IBM VisualAge C++ product. Use the Open Class Class Library samples to understand the classes and their use. Complete listings are included in the `..\samples\ioc` directory.

#### About the Hello World Application

The Hello World sample application is divided into several versions, starting with the simplest form, version 1, and building up to the most complicated form, version 6. Each version shows you a different aspect of the Open Class Class Library.

Hello World Version 1: Creating a Main Window through Hello World Version 6: Adding a Font Dialog, Pop-up Menus, Notebooks, and Graphics show you how to build an application, called "Hello World", using the Open Class Class Library. These sample applications do not teach you C++ programming. If you are not familiar with the principles and aspects of C++ programming, consult the C/C++ Language sections in the Reference section of the help before continuing with this section.

The samples provided are portable between the operating systems we provide. Application resources are targetted for the platforms on which they are to be built.

You can also take advantage of native controls by specifying a style. The figures accompanying many samples show the CUA '91 (PM compatible) controls and the native controls you can produce using the samples.

#### Reviewing the Conventions Used in the Samples

The Open Class Class Library uses conventions to enhance the usability and readability of the code. The following conventions will help you as you create applications.

- Class names begin with a capital letter. For example, all classes belonging to the Open Class Class Library with a global scope begin with the letter "I", as in IApplication. If a class name consists of more than one word, the first letter of each word is capitalized, such as IFrameWindow.

  In keeping with this standard, the letter "A" was chosen as the first letter (for example, AHelloWindow) for the Hello World application-defined classes. This convention helps you distinguish the Hello World application classes from the Open Class Class Library classes. This naming convention also helps you distinguish the classes you create from those supplied by the class library.

- Member functions begin with a lowercase letter. If a member function name consists of more than one word, the first letter of each word that follows the first word is capitalized, such as setText.

  Note: | In this infomation, single-word member functions have ClassName:: added to them; for example, the member function "show" appears as IWindow::show.

Hello World Version 1: Creating a Main Window
Hello World Version 2: Adding Resource Files and Frame Extensions
Hello World Version 3: Adding Command Handlers and Menu Bars
Hello World Version 4: Adding Dialogs and Push Buttons
Hello World Version 5: Adding Canvases, a List Box, Native System Functions, and Help
Hello World Version 6: Adding a Font Dialog, Pop-up Menus, Notebooks, and Graphics