ppt lesson 09

Microsoft Visual Basic 2005 BASICS

Lesson 9

Nested If Statements and Radio Buttons

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Objectives

Use nested If statements. Use radio buttons. Use the Form Load event. Use the Select Case statement.

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Using Nested If Statements

Nested If statement An If statement placed inside another If

statement When using nested If statements

It is important that you properly indent the code.

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Using Nested If Statements (cont.)

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Using Nested If Statements (cont.)

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Using Radio Buttons

Radio buttons are similar to check boxes with one important difference. Radio buttons appear in groups. Only one button can be selected at a time.

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Using Radio Buttons (cont.)

Using radio buttons Create a GroupBox to group the radio

buttons. Create the radio buttons in the GroupBox. Write code to use the radio buttons.

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Using Radio Buttons (cont.)

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Creating a GroupBox Control

GroupBox control Container for other controls

Controls that you place inside a GroupBox are treated as one unit.

Option group Radio buttons in a GroupBox

GroupBox most important properties (Name) and Text

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Creating a GroupBox Control (cont.)

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Creating a GroupBox Control (cont.)

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Creating Radio Buttons in the GroupBox

Once the GroupBox is created Add radio

buttons to the GroupBox.

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Setting Radio Button Name and Text Properties

Radio buttons need to be named appropriately. Use the Name property

The Text property Specifies the message for the attached

label

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Setting Radio Button Name and Text Properties (cont.)

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Adding Code to the Radio Buttons

Coding radio buttons Requires that you think in an event-driven

way Use form-level variables as the scope.

To keep track of the option that has been selected

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Adding Code to the Radio Buttons (cont.)

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Processing the Data

The final step Calculate the result and create the output.

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Using a Form Load Event Procedure

Set the Checked property to True. The radio button is selected.

When a form is loaded and opened A special event called a Load event is

triggered. You can write an event procedure for the

form’s Load event.

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Using Select Case

In a Select Case statement You specify a variable to test. You then list a number of cases for which

you want to test. The first line in a Select Case

statement Specifies the data involved in the decision

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Using Select Case (cont.)

You can use conditional operators in a Case statement.

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Summary

If statements can be nested to make additional decisions within the code of the If statement.

It is important to indent the code in a nested If statement to make the code readable.

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Summary (cont.)

Each If statement within a nested If statement must end with the End If statement.

Radio buttons appear in groups. Only one radio button in the group can be selected at a time.

Radio buttons are sometimes called option buttons.

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Summary (cont.)

The first step in creating a group of radio buttons is to create a GroupBox control to contain the radio buttons. The controls within a GroupBox are treated as one unit.

The Text property of a GroupBox control specifies the text that appears at the top of the GroupBox.

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Summary (cont.)

To associate a radio button with a GroupBox, click the RadioButton tool only once and draw the radio button in the GroupBox. If you double-click to create a radio button, it will not associate itself with the GroupBox.

The Text property of a GroupBox control specifies the text that appears on the label attached to the radio button.

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Summary (cont.)

Coding radio buttons involves using form-level variables that carry values that reflect the selected radio button.

A form’s Load event procedure is executed each time a form is loaded and opened by the program.

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Summary (cont.)

The Select Case statement allows you to make multi-way selections. The Case statements in a Select Case can test a range or use conditional operators.

Conditional operators in a Case statement must include the Is keyword.

As a default, the Case Else statement is applied if no other Case is true.