Introduction

In this chapter, we will show you how to understand complex Visual Basic Applications that contain multiple modules and procedures that require sharing data between each other. When writing complex applications, you must be able to share data between procedures and modules by declaring the variables appropriately and by writing procedures in such a way that other procedures can access them.

Moreover, you will use VB's internal functions to perform common analysis and data manipulation of strings, numbers, and other kinds of data.

Mastering Program Structure

By now you must have a good idea of how VB programs operate. When the user interacts with controls, events take place. The VB program code is a set of event procedures with a Declarations section at the beginning of the code.

Event procedures are not the only procedures that can appear in code.

A Form Module might contain declarations section, event procedures, general procedures, and class procedures.

A general procedure is a procedure that is not linked to a control event but performs general calculations. A general procedure can be function or subroutine procedures. For example, if you want to call a general procedure named Calc(), you can call it like this

Call calc()

The call statement transfers control to a Sub procedure, Function procedure, or dynamic link library (DLL) procedure.

A class is a description of a set of characteristics. In other words, a class defines a new data type or variable. The class contains class procedures.