Chapter

Introduction to Programming

and Visual Basic 2010 1

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Slide 1- 2

Overview

Topics

Introduction

Computer Systems

Hardware and Software

Programs and Programming Languages

Controls and Programming

Programming Process

Visual Studio

Slide 1- 3

Introduction

With Visual Basic

You may create applications that

Provide graphical windows, dialog boxes, menus

Work with databases

Use internet technologies

Display graphics

Computer Systems:

Hardware and Software 1.1

Computer systems consist of similar

hardware devices and components

Computer Hardware

Computer hardware

Refers to physical components

Central Processing Unit (CPU)

Main memory

Secondary storage devices

Input devices

Output devices

Slide 1- 5

Organization of a Computer System

Input

keyboard

mouse

scanner

microphone

digital camera

disk drives

Output

monitor

printer

speakers

disk drives

Slide 1- 6

Central Processing Unit

Central Processing Unit (CPU)

Fetches instructions from program in main

memory

Part of program stored as binary numbers

(sequences of 0's and 1's)

Carries out operations commanded by

instructions

Each instruction produces some outcome

Slide 1- 7

Main Memory

RAM (Random Access Memory)

Sequentially numbered storage locations

Holds instructions and data needed for

programs currently running

Usually volatile (contents lost when power is

turned off)

Used as temporary storage

Slide 1- 8

Secondary Storage

Secondary storage

Nonvolatile storage (contents retained while

power is off)

Usually a disk drive (magnetic storage)

Hard disks, floppy disks

CDs, DVDs

Flash drives

Slide 1- 9

Input Devices

Input devices

Provide data to computer from outside world

Examples

Keyboard

Mouse

Scanner

Microphone

Slide 1- 10

Output Devices

Output devices

Provide data from computer information to

outside world

Image, printed report, sound

Examples

Monitor (display screen)

Printer

Speakers

Slide 1- 11

Software

Software

Programs that run on a computer

Operating systems

Controls processes within computer

Manages computer's hardware devices

Application software

Solves problems or performs tasks needed by users

Examples

Word processing, spreadsheets, games, Internet

browsers, playing music

Slide 1- 12

Programs and

Programming Languages 1.2

A program is a set of instructions that a computer

follows in order to perform a task.

A programming language is a special language used

to write computer programs.

What Is a Program?

Computer program

Set of instructions on how to solve a problem

or perform a task

Example

In order for a computer to calculate someone’s

gross pay, we must tell computer to perform the

following steps

Slide 1- 14

Computing Gross Pay

Steps to compute gross pay

1. Display message on screen: "How many

hours did you work?"

2. Allow user to enter hours worked

3. Store number in memory

4. Display message on screen: "How much are

you paid per hour?"

5. Allow user to enter hourly pay rate

6. Store number in memory

Slide 1- 15

Computing Gross Pay (cont.)

7. Multiply hours worked by hourly pay rate and

store result in memory

8. Display a message on screen with result of

previous step

Note: This well-defined, ordered set of steps for

solving a problem is called an algorithm

Slide 1- 16

Slide 1- 17

Pseudocode

Start

output "How many hours did you work?"

input hoursWorked

output "How much are you paid per hour?"

input hourlyPayRate

grossPay = hoursWorked * hourlyPayRate

output "You earned ", grossPay

Stop

Slide 1- 18

Flowchart Start

Print “How many

hours did you work?”

Input hoursWorked

grossPay = hoursWorked *

hourlyPayRate

Print “How much are

you paid per hour?”

Input hourlyPayRate

Print “You earned “,

grossPay

Stop

States and Transitions

Memory snapshots show states of program

3. Store hours worked in memory

6. Store hourly pay rate in memory

7. Multiply hours worked by hourly pay

rate and store gross pay in memory

Slide 1- 19

Program Starting State

hours worked

hourly pay rate

gross pay

??

??

??

Snapshot after Step 3

hours worked

hourly pay rate

gross pay

20

??

??

Snapshot after Step 6

hours worked

hourly pay rate

gross pay

20

25

??

Snapshot after Step 7

hours worked

hourly pay rate

gross pay

20

25

500

Slide 1- 20

Terms

Algorithm

Well-defined, ordered set of steps for solving a

problem

Algorithm

al·go·rithm noun

a set of rules for solving a problem in a finite number of

steps, as for finding the greatest common divisor.

http://dictionary.reference.com/browse/algorithm

Slide 1- 21

Algorithm (cont.)

In mathematics and computer science, an algorithm is an

effective method expressed as a finite list[1] of well-defined

instructions[2] for calculating a function.[3] Algorithms are

used for calculation, data processing, and automated

reasoning. In simple words an algorithm is a step-by-step

procedure for calculations.

http://en.wikipedia.org/wiki/Algorithm

Slide 1- 22

Computer Program

pro·gram noun

a. a systematic plan for the automatic solution of a

problem by a computer.

b. the precise sequence of instructions enabling a

computer to solve a problem.

http://dictionary.reference.com/browse/program

Slide 1- 23

Computer Program (cont.)

A computer program (also software, or just a program)

is a sequence of instructions written to perform a specified

task with a computer.[1] A computer requires programs to

function, typically executing the program's instructions in a

central processor.[2] The program has an executable form

that the computer can use directly to execute the

instructions. The same program in its human-readable

source code form, from which executable programs are

derived (e.g., compiled), enables a programmer to study

and develop its algorithms.

http://en.wikipedia.org/wiki/Computer_program

Slide 1- 24

Slide 1- 25

Terms (cont.)

Machine language

Series of 1’s and 0’s computer understands

Programming language

Allows programmers to use words instead of

numbers

Compiler

Converts programming language statements to

machine language

Slide 1- 26

Common Programming Languages

Procedural

BASIC

C

COBOL

FORTRAN

Pascal

Object-Oriented

C++

C#

Java

Visual Basic

Language Elements

Programs are comprised of

Keywords

Words with special meaning to Visual Basic (e.g., Private, Sub)

Programmer-defined names

Names created by programmer (e.g., grossPay, btnClose)

Operators

Symbols to perform common operations

(e.g., +, -, *, /)

Slide 1- 27

Language Elements (cont.)

Statements

Instructions made up of keywords, identifiers, and

operators

Procedures

Set of programming statements that perform a

single task

Comments

Program documentation inserted by developer and

ignored when program runs

Begin with ' and continue to end of line

Slide 1- 28

Language Elements: Syntax

Syntax

Rules of language

Syntax of Visual Basic

Defines correct use of keywords, operators, and

programmer-defined names

A program that violates the rules of syntax will not

run until corrected

Syntax of English

Defines correct use of nouns, verbs, etc.

Slide 1- 29

Slide 1- 30

Methods of Programming

Procedural

Constructed as set of procedures

(operational, functional units)

Each procedure is a set of instructions

Object-Oriented

Constructed as set of real-world objects

i.e. students, transcripts, and courses

Objects have data elements (attributes) and

perform actions (methods)

Example of an Object

Graphical User Interface (GUI) object called a

form

Data include

hours worked

hourly pay rate

gross pay

Actions include

Calculating gross pay in a method that

determines how form reacts

Slide 1- 31

Example of an Object (cont.)

Form elements are

objects called controls

Sample form has

2 TextBox controls

4 Label controls

2 Button controls

A controls’s Text property holds the value

displayed by the control

Text property of left button is Calculate Gross Pay

Buttons have methods attached to click events Slide 1- 32

Event Driven Programming

Event

Action that takes place within a program

Examples

Mouse click, text change

Visual Basic controls are capable of detecting

events

Program can respond to an event if

programmer writes an event procedure

Slide 1- 33

More About Controls and

Programming 1.3

As a Visual Basic programmer, you must design and

create the application’s

1) GUI elements (forms and other controls)

2) programming statements that respond to and/or

perform actions (event procedures)

Visual Basic Controls

Windows users are familiar with many controls

Label - displays text user cannot change

TextBox - allows user to enter text

Button - performs an action when clicked

RadioButton - round button selected or

deselected with a mouse click

CheckBox - box checked or unchecked with a

mouse click

Form - window that contains controls

Slide 1- 35

Tutorial 1-3, Visual Basic Controls

Slide 1- 36

Name Property

All controls have properties

Each property has a value (or values)

Every control has a Name property

Value of Name property is used to reference

the control in a program

Controls are assigned default names when created

Programmers usually change these names to

meaningful names

Slide 1- 37

Examples of Names

Labels use default names (i.e. Label1)

Text boxes, buttons, and Gross Pay label play an

active roles in program and have been changed

Slide 1- 38

btnCalcGrossPay btnClose

txtHoursWorked

txtPayRate

lblGrossPay

Label1

Label2

Label3

Form1

Slide 1- 39

Naming Rules

Naming rules

Control names must start with a letter

Remaining characters may be letters, digits, or

underscores

Slide 1- 40

Naming Conventions

Naming conventions

Use prefix to indicate type of control

txt for Text Boxes

lbl for Labels

btn for Buttons

Select a descriptive name

Use camel-casing

i.e. txtHoursWorked is clearer than txthoursworked

Event Handler – Compute Gross Pay

Slide 1- 41

' Procedure for click event on btnCalcGrossPay

Private Sub btnCalcGrossPay_Click(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles btnCalcGrossPay.Click

' Define variable to hold gross pay

Dim grossPay As Double

' Convert values in text boxes to numbers, and calculate gross pay

grossPay = Convert.ToDouble(txtHoursWorked.Text) *

Convert.ToDouble (txtPayRate.Text)

' Format gross pay for currency display and assign it to Text

' property of label

lblGrossPay.Text = grossPay.ToString("C")

End Sub

Event Handler - Close

Slide 1- 42

' Procedure for click event on btnClose

Private Sub btnClose_Click(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles btnClose.Click

'End the program by closing its window

Me.Close()

End Sub

Programming Process

1.4

The programming process consists of design,

creation, testing, and debugging activities

Step 1 of Developing an Application

Clearly define what the program is to do

Example Wage Calculator program

Purpose: to calculate user’s gross pay

Input: number of hours worked, hourly pay rate

Process: multiply number of hours worked by hourly pay

rate resulting in gross pay

Output: display a message indicating computed gross

pay

Slide 1- 44

Step 2 of Developing an Application

Visualize application running on the computer

and sketch its user interface

Slide 1- 45

Step 3 of Developing an Application

List controls needed

Slide 1- 46

Type Name Description

TextBox txtHoursWorked Allows the user to enter the number of hours worked.

TextBox txtPayRate Allows the user to enter the hourly pay rate

Label lblGrossPay Displays the gross pay, after the btnCalcGrossPay

button has been clicked

Button btnCalcGrossPay When clicked, multiplies the number of hours worked

by the hourly pay rate

Button btnClose When clicked, terminates the application

Label (default) Description for Number of Hours Worked TextBox

Label (default) Description for Hourly Pay Rate TextBox

Label (default) Description for Gross Pay Earned Label

Form (default) A form to hold these controls

Step 4 of Developing an Application

Define values for each control's relevant properties

Slide 1- 47

Control Type Control Name Text

Form (Default) "Wage Calculator"

Label (Default) "Number of Hours Worked"

Label (Default) "Hourly Pay Rate"

Label (Default) "Gross Pay Earned"

Label lblGrossPay "$0.00"

TextBox txtHoursWorked ""

TextBox txtPayRate ""

Button btnCalcGrossPay "Calculate Gross Pay"

Button btnClose "Close"

Step 5 of Developing an Application

List event handlers needed for each control

Slide 1- 48

Method Description

btnCalcGrossPay_Click Multiplies hours worked by hourly pay rate

These values are entered into txtHoursWorked

and txtPayRate TextBoxes. Result is stored in

lblGrossPay Text property.

btnClose_Click Terminates the application

Slide 1- 49

Step 6 of Developing an Application

Create pseudocode or flowchart of each method

Pseudocode is an English-like description in

programming language terms

Compute grossPay as numberOfHoursWorked times

hourlyPayRate

Assign to lblGrossPay.Text the value in grossPay

Slide 1- 50

Step 6 of Developing an Application (cont.)

Flowchart is a diagram that graphically depicts

the flow of the method

Start End

Multiply hours

worked by

hourly pay

rate, store

result in

grossPay

Copy value in

grossPay to

lblGrossPay

Text property

Step 7 of Developing an Application

Desk check code for errors

Read flowchart and/or pseudocode

Step through each operation as if you are the

computer

Use paper to jot down values of variables and

properties as they change

Verify that expected results are achieved

Slide 1- 51

Step 8 of Developing an Application

Use Visual Basic to create GUI (Graphical User

Interface)

Forms and other controls identified in step 3

Note: This is first use of Visual Basic. All previous steps

have just been on paper. In this step you develop

portion of application that the user will see.

Slide 1- 52

Step 9 of Developing an Application

Use Visual Basic to write code for

Event procedures

Other methods created in step 6

Note: This is second use of Visual Basic. In this step you

develop methods behind click events for buttons. This

portion of application the user will not see.

Slide 1- 53

Step 10 of Developing an Application

Attempt to run the application - find syntax errors

Correct any syntax errors found

Repeat this step as many times as needed

Note: All syntax errors must be removed before Visual

Basic will create a program that actually runs

Slide 1- 54

Step 11 of Developing an Application

Run application using test data as input

Run the program with a variety of test data

Check results to be sure that they are correct

(Incorrect results are referred to as runtime

errors)

Correct any runtime errors found

Repeat steps 10 and 11 as often as necessary

Slide 1- 55

Visual Studio and the

Visual Basic Environment 1.5

Visual Studio consists of tools that you use to build

Visual Basic applications

Visual Studio IDE

Visual Studio

Integrated Development Environment (IDE)

Provides tools needed to create, test, and debug software applications

Form designer to create the user interface

Code editor and compiler

Visual Basic, C# languages

Debugger to help find and correct programming

errors

Slide 1- 57

Visual Basic Environment

Tutorial 1-4 introduces elements of the IDE

Customizing the IDE

Windows

Design – design and create a form

Solution Explorer – shows files in solution

Properties – modify properties of an object

Dynamic Help – handy reference tool

Toolbox – objects used in form design

Toolbar – icons for frequently used functions

Tooltip – short description of icon’s purpose

Slide 1- 58

Creating a VB Application

To create an application

Open Visual Studio

Create a New Project

Create a New VB .NET Windows Application

Add Controls to Design Window

Add Code for Event Procedures

Build Project

Run Code

View Results

Slide 1- 59

Launching Visual Studio

Slide 1- 60

VS 2010 - Start Page

Create a New Project

New Project

New Project: VB Windows Forms Application

Design Window

Design Window

Solution Explorer

Properties Window

Toolbox

Slide 1- 65

Visual Basic Environment

Environment

Toolbox

Design Window

Solution Explorer Window

Properties Window

Dynamic Help Window

Docked and Floating Windows

Toolbox, Form with Controls, Properties

Title Bar

Menu Bar

Toolbox

Standard Toolbar

Properties Window

Code Window

Building the Code

Build Solution/Project

Running the Code

Run/Start Debugging

Sample Run

Code

' Compute Wages Code

Private Sub btnCalcGrossPay_Click(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles btnCalcGrossPay.Click

' declare variable to hold computed wages

Dim hoursWorked As Double

Dim hourlyRate As Double

Dim grossPay As Double

Double.TryParse(txtHoursWorked.Text, hoursWorked)

Double.TryParse(txtHourlyPayRate.Text, hourlyRate)

' compute gross pay based on hours worked and hourly pay rate

grossPay = hoursWorked * hourlyRate

' display gross pay

lblGrossPayEarned.Text = grossPay.ToString("c")

End Sub

Private Sub btnClose_Click(ByVal sender As System.Object,

ByVal e As System.EventArgs) Handles btnClose.Click

' close form to end application

Me.Close()

End Sub

Slide 1- 71

Code

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click

' clear text fields

txtHoursWorked.Clear()

txtPayRate.Clear()

lblGrossPay.Text = String.Empty

' set focus to hours worked

txtHoursWorked.Focus()

End Sub

Slide 1- 72

Slide 1- 73

Summary

Topics covered

Introduction

Computer Systems

Hardware and Software

Programs and Programming Languages

Controls and Programming

Programming Process

Visual Studio