VB.NET_-_Module_3_Language_and_Syntax_Enhancements.pdf

Module 3: Language

and Syntax

Enhancements

Contents

Overview

Data Types

Using Variables

Demonstration: Using Variables and Data

Structures

Functions, Subroutines, and Properties

Lab 3.1: Working with Variables and

Procedures

Exception Handling

Demonstration: Structured Exception

Handling

Lab 3.2: Implementing Structured

Exception Handling

Review

This course is based on the prerelease version (Beta 2) of Microsoft® Visual Studio® .NET

Enterprise Edition. Content in the final release of the course may be different from the

content included in this prerelease version. All labs in the course are to be completed with

the Beta 2 version of Visual Studio .NET Enterprise Edition.

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Module 3: Language and Syntax Enhancements

iii

Instructor Notes

Presentation:

90 Minutes

This module provides students with the knowledge needed to use many of the

new language and syntax enhancements to the Microsoft ® Visual Basic ®

language, including variable declaration and initialization, procedure syntax,

structured exception handling, and assignment operator changes.

Labs:

75 Minutes

In the labs, students will create a simple application that uses variables and

procedures to add customers to a customer array. The students will then add

structured exception handling to the application.

After completing this module, students will be able to:

¡ Describe the changes to data types in Visual Basic .NET.

¡ Declare and initialize variables and arrays.

¡ Use shorthand syntax to assign values to variables.

¡ Implement functions and subroutines.

¡ Call the default properties of an object.

¡ Use the new Try…Catch…Finally statement to implement structured

exception handling.

Materials and Preparation

This section provides the materials and preparation tasks that you need to teach

this module.

Required Materials

To teach this module, you need the following materials:

¡ Microsoft PowerPoint ® file 2373A_03.ppt

¡ Module 3, “Language and Syntax Enhancements”

¡ Lab 3.1, Working with Variables and Procedures

¡ Lab 3.2, Implementing Structured Exception Handling

Preparation Tasks

To prepare for this module, you should:

¡ Read all of the materials for this module.

¡ Read the instructor notes and the margin notes for the module.

¡ Practice the demonstrations.

¡ Complete the labs.

Module 3: Language and Syntax Enhancements

Demonstrations

This section provides demonstration procedures that will not fit in the margin

notes or are not appropriate for the student notes.

Using Variables and Data Structures

è To test the application

1. Open the DataTypes.sln file in the install folder \DemoCode\

Mod03\DataTypes folder.

2. In the code for frmData.vb, set breakpoints on the first lines of the

TestVariables and TestStructures subroutines.

3. Run the project.

è To debug the Variables button

1. Click the Variables button on the form. The Visual Basic process will halt

at the first breakpoint.

2. Explain the code, pointing out that both intA and intB are created as Integer

data types.

3. Step through the code by using F11, and explain the new assignment

operators and the CType function.

4. Allow the program to continue by pressing F5.

5. Stop the project and uncomment the Option Strict code at the top of the

form code. Attempt to run the project. A compilation error will occur.

Explain why this occurs. Re-comment the Option Strict code, and run the

project to test the Structures code.

è To debug the Structures button

1. Click the Structures button on the form, and step through the

TestStructures subroutine. Point out the Employee structure definition at

the top of the form code before continuing to debug. Note that the array is

initialized to a size of two employees. Continue debugging the code by

using F11. Explain each line when required.

2. Point out the block-level variable iCounter . Allow the remaining code to

execute before closing the form and stopping the debugger.

è To create an out-of-scope variable exception

1. Return to the form code and uncomment the final line in the TestStructures

routine MsgBox( iCounter ) . Attempt to run the project again, and observe

the error message that is generated because of the attempt to access the

block-level variable outside of its scope.

2. Close the Microsoft Visual Studio ® .NET integrated development

environment (IDE).

Module 3: Language and Syntax Enhancements

Structured Exception Handling

è To test the application

1. Open the Exceptions.sln solution in the install folder \DemoCode\

Mod03\Exceptions folder.

2. Open the code window for the Errors.vb form and set breakpoints on the

Try statement, each Catch statement, and the Finally statement in the

RunExceptions routine.

3. Run the Exceptions project.

4. Click the Overflow button on the form. The Visual Basic process will halt

at the first breakpoint.

5. Use F11 to step through the code in the Try block, and explain the overflow

details. Explain that the OverflowException class is filtering the exception.

Step through the remaining code, and allow execution to continue.

6. Click the remaining buttons on the test form ( Divide , Err.Raise , and

Throw ) to demonstrate how the exceptions are handled in each case.

7. End the debugging session by closing the form.

8. Close the Visual Studio .NET IDE.

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