CPS613	VB .NET Techniques and References
	Miscellaneous Information

Table of Contents

• Arrays and Loops in VB
• Radio Buttons
• Random Number Generator
• Timer Component

  Dim radios(4) As RadioButton

  radios(0) = RadioButton1
  radios(1) = RadioButton2
  radios(2) = RadioButton3
  radios(3) = RadioButton4  

Both links in this section include good examples.

This functionality is well supported in Visual Studio but because it is unusual to design built-in controls that must work as a group, this requires some additional (minimal) work:

• Each radio button is a RadioButton control defining a RadioButton class

• To create a bank of radio buttons that work together, these radio buttons must belong to the same Container control. You can see a list of such controls in the Toolbox section called "Containers". This includes TabControls, so if you are dragging a group of RadioButtons onto the same TabPage of a TabControl, they will automatically work together. For more details see: How to: Group Windows Forms RadioButton Controls to Function as a Set.

• All the radio buttons are intended to behave in a very similar fashion. This is implemented by writing a single handler to handle the same event for all the radio buttons in the same bank. This is usually done for the Click event.

  When you share a single handler between multiple controls, the parameter called sender is the control that invoked the event, i.e. the one that the user selected. As you will notice, sender is of type System.Object, so if you would like to acccess properties or methods for this control, you will first need to cast sender to the correct control type. In VB, there is no direct casting like in C or Java. Instead you can copy the variable of a generic type into another of a more specific type. So for example, if you are certain that sender is a RadioButton and you would like to access a RadioButton property or method, you can simply do the following:

         Dim button As RadioButton = sender

  then use button instead of sender.

  Information that is specific to the clicked radio button can be found primarily in the Text property of that button since this is where the choice made by the user is described. VB has a few useful conversion functions to convert strings to other types of variables, in particular Cint can convert text to an integer. However, if it is not convenient to work with strings, the Tag property can be used to store (at design or code time) other more useful information like a key or index.

Timer Component