Illuminating Computer Science CCIT 4-6Sep

Illuminating Computer Science CCIT 4-6Sep http://www.aast.edu/en/colleges/ccit/cs4hs/

Introduction to Introduction to Programming ConceptsProgramming Concepts

Visual Basic: an Introduction



ObjectivesObjectives

The audience should be familiar with the Visual Basic Environment.

The audience should be able to build simple Visual Basic Applications.

The audience should learn the precedence rules for writing equations.

The audience should be able to write programs using control structures


Performing a Task on the Performing a Task on the ComputerComputerDetermine OutputIdentify InputDetermine process necessary to turn

given Input into desired Output


Problem-solving approach like Problem-solving approach like algebra classalgebra classHow fast is a car traveling if it goes

50 miles in 2 hours?Output: a number giving the rate of

speed in Km per hourInput: the distance and time the car

has traveledProcess: rate = distance/time


Pictorial representation of the Pictorial representation of the problem solving processproblem solving process


Program Planning TipsProgram Planning Tips

Always have a plan before trying to write a program

The more complicated the problem, the more complex the plan must be

Planning and testing before coding saves time coding


Simplified Program development Simplified Program development cyclecycle

1. Analyze: Define the problem.

2. Design: Plan the solution to the problem.

3. Choose the interface: Select the objects (text boxes, buttons, etc.).


Program development cycle Program development cycle continuedcontinued4. Code: Translate the algorithm into a

programming language.Try to avoid jumping straight to this step, which can result in a sloppy solution!

5. Test and debug: Locate and remove any errors in the program.

6. Complete the documentation: Organize all the material that describes the program.


What is Visual Basic?What is Visual Basic?

High Level 4th Generation Programming Language

Object and Event DrivenVisual - Windows Based Integrated Development Environment

or IDE


What is VB Used For?What is VB Used For?Most Popular Programming LanguageStand alone programsApplets that can be run on many

different kinds of computersCustomized specialized Applications

– E- Commerce • Web based shopping forms and inquiries

User friendly Interface to applications


Used by a computer equipment retail outlet to record data regarding customer orders.

Example Order Entry Example Order Entry ScreenScreen

Allows user to use a mouse to click on boxes for text entry.

Also enables user to click on buttons to initiate processing steps.


Generations of Computer LanguagesGenerations of Computer Languages

1st - Machine language - 0110 0011 1000

2nd - Procedure-oriented languages – FORTRAN - 1954 for scientists and engineers

– COBOL - 1959 for business applications

– C - 1972 - for UNIX operating systems

3rd - Object-oriented languages4th - Event-driven languages - i.e.VB5th - Natural languages i.e. English


Compiler Vs InterpreterCompiler Vs Interpreter

Higher Languages are translated to Machine Language by:– Interpreter

• Translates instructions to machine code line-by-line.

• BASIC, Quick Basic, Visual Basic

– Compiler • Translates the entire program to machine

code before running it.• Fortran, C, C++, Visual Basic is also a compiler


What are the Objects in VB?What are the Objects in VB?

Pre-programmed Code for:– Command Buttons– Labels– Pictures– Text Boxes

Have both data and procedures wrapped together


What are the Events?What are the Events?

– Visual Basic “watches” what the user does

– A user activity is called an event– Events include mouse clicks and

moves, menu selections, button presses, etc.

– Sections of code are only executed in response to an event


What is the Integrated Development What is the Integrated Development Environment (IDE)?Environment (IDE)?


Visual Basic EnvironmentVisual Basic Environment

GUI (Graphical User Interface) - forms and windows that the user sees

Property - a characteristic or attribute of an object such as color and size

Event - a user action such as clicking a button

Code Editor window - editor specially designed to help you when writing code


Visual Basic EnvironmentVisual Basic EnvironmentComponents of the VB design

environment (Form view)


Visual Basic EnvironmentVisual Basic EnvironmentComponents of the VB design

environment (Code view)


The Code Editor WindowThe Code Editor WindowObject List Box

Procedure List Box

Auto List Members

Full Module View button


The Code Editor WindowThe Code Editor Window

Help window

Error message box

Syntax error in Red

Procedure view button


VB Environment: Project VB Environment: Project WindowWindow

The Project Window can be used to navigate between the code and form window for each form / window a project has


VB Environment: Menu BarVB Environment: Menu Bar

The Menu Bar consists of 3 elements the–Title Bar, which holds the name of application,

default if Microsoft Visual Basic [design]–Menu Bar, this is the link to Visual Basics menu

facilities, each menu option drops down into sub-menus

–Toolbar, contains icons which give access to the more commonly used commands (which are also available through the menu bar)

Title bar Menu Bar Toolbar


VB Environment: Properties VB Environment: Properties WindowWindowUsed to set how a

control looks andbehaves

Holds its default values


VB Environment: Control VB Environment: Control ToolboxToolbox

Pointer

Label

Group Frame

Check Box

Combo Box

Horizontal Scroll Bar

Timer

Directory List Box

Shape

Image

OLE

Picture

Text Box

Command Button

Option/Radio Button

List Box

Vertical Scroll Bar

Drive List Box

File List Box

Line

Data Control


VB Environment: Context VB Environment: Context Sensitive Help Sensitive Help Context sensitive help is very usefulSelect the item control that you want help onPress the F1 key

F1


The File MenuThe File Menu

Project commands

Make executable commands

Most recent project list

Exit command



New Project Open Project Add Project Remove Project Save Project Save Project As

Save Component Save Component

As Print Print Setup



Template - particular pattern for a project or a project element; start a project from a template saves time

Existing tab - displays VB projects

Recent tab - displays most recently accessed projects

Project Groups - a collection of several projects


Building Your First ApplicationBuilding Your First Application

There are three primary steps in building a Visual Project:– Place (or draw) controls on the form.– Assign properties to the controls.– Write event procedures for the controls.


Project FilesProject Files

vbp extension = Visual Basic Project– file that tracks all components

frm extension = Form file– separate file for each form

frx extension = Binary form file– cannot be read by humans

vbw extension = Visual Basic workspace


Starting Visual BasicStarting Visual Basic


Choosing Project TypeChoosing Project Type


Placing Controls on the Form: ImagePlacing Controls on the Form: Image


Assigning Properties to ControlsAssigning Properties to Controls


Adding an ImageAdding an Image


Browse for an ImageBrowse for an Image


Image DisplayedImage Displayed


Buttons and Text BoxesButtons and Text Boxes


Changing the Form TitleChanging the Form Title


Writing the Code (Events)Writing the Code (Events)


Running the ApplicationRunning the Application


More Complex StructuresMore Complex Structures


Syntax BoxesSyntax Boxes

Syntax for a Visual Basic statement is shown in a syntax box

Reserved words are shown in boldProgrammer named words are shown in

italics


The Sub StatementThe Sub Statement

Private Sub controlname_eventname( )

Statements

End SubWhere

Private is the default procedure type

Sub indicates beginning of procedure

controlname is name of associated control

_ (underscore) required separator

eventname is name of corresponding event

( ) set of parentheses is required

End Sub indicates end of a procedure


The Sub StatementThe Sub Statement

Example

Private Sub cmdCalcTriangle_Click

Dim Base As Single

Dim Height As Single

Dim Height As Single

Area = 1 / 2 * (Base * Height)

End Sub


Declarations, Variables, Declarations, Variables, and Constantsand Constants

Variable - a uniquely named storage location that contains data that changes during program execution

Constant - a uniquely named storage locations that contains data that does not change during program execution


Declarations, Variables,Declarations, Variables,and Constantsand Constants

Rules for Naming Variables– Must begin with an alphabetic character– Can’t contain a period or type-declaration

characters such as %, &, !, #, @ or $

– Must be unique with same scope– Must be no longer than 255 characters– Should not reserved word (See Appendix A)


Declaring VariablesDeclaring Variables

Declaration statement - nonexecutable code that sets aside storage locations for future use

Local variables - declared within a procedure or function

Global variables - declared in the general section of the application



Declare variables using the Dim or Static statementsDim statement - value of variable

preserved only until procedure ends

Static statement - value of variable preserved the entire time the application is running


The Dim StatementThe Dim Statement

Dim variablename As datatype

Where

Dim is required

variablename should be a descriptive name

As is required

datatype is one of the following types:

Boolean, Byte, Date, Integer, Long, Single,

Double, Currency, String, Object or Variant



Data Types– Boolean - True or false– Date - From Jan 1, 100 to Dec 31, 9999– Integer - Numbers without a decimal point– Long - Long integer– Single - Numbers with a decimal point– Double - Long Single– Currency - Dollar amounts– String - Character and alphanumeric data– Object - Any object reference such as Word document– Variant - default, can hold any data type


Assigning Values to VariablesAssigning Values to Variables

Variablename = value

Where

variablename is the descriptive name of the variable

= is the assignment operator

value is the value the variable will contain

Examples:Number1 = 5FirstName = “Steve”LoanAmount = 67.38Length = 17.8

Note: Order is important. Variable name always on the left, and value on the right.


Declaring Constants Declaring Constants

Const constantname As datatype = value

Where

Const is required

constantname is the descriptive name of the constant

As is required

datatype is the type of data the constant will contain

= is the assignment operator

value is the value of the constant

Examples:Const Pi As Single 3.14159265358979Const MaxNumber As Integer = 100


FunctionsFunctions

Function - unit of code that returns a value

Built-in Functions– Sqr - square root– Rnd - random number generator– Int - returns integer portion of a number– Val - converts a string to a value– Str - converts a value to a string


Application 1: Calculate the area of Application 1: Calculate the area of a circlea circle Inputs: radius of the circle r Output: area of the circle Process: Area=

2r


Application 1: Calculate the area of Application 1: Calculate the area of a circle (Form View)a circle (Form View)


Application 1: Calculate the area of Application 1: Calculate the area of a circle (Code View)a circle (Code View)


Application 1: Calculate the area of Application 1: Calculate the area of a circle (Run)a circle (Run)


Precedence TablePrecedence Table

Operator

( )

^

*, /

+,-

If precedence of two following operators is equal, then the evaluation starts from left to right.


Simple Examples of EquationsSimple Examples of Equations

Equation in normal form:– Y=3X– Y=X-10+3(X-Z)– Y=X^2*10– Y= X

Equation in VB form:– Y=3*X– Y=X-10+3*(X-Z)– Y=X*X*10– Y=SQR(X)


Application 2: Convert from Application 2: Convert from Fahrenheit Degree to Celsius Fahrenheit Degree to Celsius Original formula:

Celsius=5/9(Fahrenheit-32)Visual Basic formula:

Celsius=5/9*(Fahrenheit-32)Input: FahrenheitOutput: CelsiusProcess: Celsius=5/9*(Fahrenheit-32)


Application 2: Convert from Application 2: Convert from Fahrenheit Degree to Celsius (Form Fahrenheit Degree to Celsius (Form View)View)


Application 2: Convert from Application 2: Convert from Fahrenheit Degree to Celsius (Code Fahrenheit Degree to Celsius (Code View)View)


Application 2: Convert from Application 2: Convert from Fahrenheit Degree to Celsius (Run)Fahrenheit Degree to Celsius (Run)


Application 3: The Wind Chill Application 3: The Wind Chill ApplicationApplicationWrite a program that calculates

the wind chill temperatureInputs: Wind Speed and TemperatureOutputs: Wind Chill Temperature


Application 3:The Wind Chill Application 3:The Wind Chill ApplicationApplication Original formula

– WC = 0.0817(3.71(V **0.5) + 5.81 - 0.25V)(T - 91.4) + 91.4

Visual Basic statement– WC = 0.0817 * (3.71 * Sqr(V) + 5.81 -(0.25 * V)) *

(T - 91.4) + 91.4 Output: Wind Chill (WC) Input 1 T: Temperature Input 2 V: Wind Speed


Adding Controls and Changing their Adding Controls and Changing their PropertiesProperties


Writing the CodeWriting the Code


Running the ApplicationRunning the Application


Control StructuresControl Structures


Controlling your ApplicationControlling your Application

Sequence

Selection– If...Then...Else statement– Select Case statement

Repetition– For...Next Loop statement– For Each...Next statement– Do Loops


Selection If..Then..ElseSelection If..Then..Else

If (condition) Then (statement[s])

[ElseIf (condition) Then (statement[s])]

[Else (statement[s])]


Selection Application: Convert from Selection Application: Convert from Numerical Grade to Letter GradeNumerical Grade to Letter Grade Input: a numeric grade between 0 and

100 Output: depends on input

Input Output

049 F

5052 D

5356 D+

5760 C-

6164 C

6569 C+

7074 B-

7579 B

8084 B+

8589 A-

90100 A


Selection Application: Convert from Selection Application: Convert from Numerical Grade to Letter Grade (Form Numerical Grade to Letter Grade (Form View)View)


Selection Application: Convert from Selection Application: Convert from Numerical Grade to Letter Grade (Code Numerical Grade to Letter Grade (Code View)View)


Selection Application: Convert from Selection Application: Convert from Numerical Grade to Letter Grade Numerical Grade to Letter Grade (Run)(Run)


For...Next Loop StructureFor...Next Loop StructureFor counter = start To end Step increment

statements

Next counter

Where

Counter is tested to see if less than end.If so, repeat loop again. If not, go to

statement after Next.


Do While...Loop StructureDo While...Loop StructureDo While condition

statements

Loop

Where

The condition is tested, and if true the loop isrepeated. When the condition is false, the loopstatements are skipped the statement after

Loopis executed.


Do Until...Loop StructureDo Until...Loop StructureDo Until condition

statements

Loop

Where

The condition is tested, and if false the loop isrepeated. When the condition is true, the loopstatements are skipped the statement after

Loopis executed.


Loops Application: FactorialLoops Application: Factorial

Factorial (N)= N*(N-1)*(N-2)……….*(1)


Factorial Flowchart (N>0)Factorial Flowchart (N>0)


Factorial Application: Form ViewFactorial Application: Form View


Factorial Application: Code ViewFactorial Application: Code ViewUsing For..Next LoopUsing For..Next Loop


Factorial Application: Code ViewFactorial Application: Code ViewUsing Do..While..LoopUsing Do..While..Loop


Factorial Application: Code ViewFactorial Application: Code ViewUsing Do..Until..LoopUsing Do..Until..Loop


Factorial Application: RunFactorial Application: Run


SummarySummary

After the completion of this lecture, the audience should be familiar with the visual basic environment and different controls.

The audience should be able to write simple programs and generate simple VB applications.

Illuminating Computer Science CCIT 4-6Sep

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