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Chapter 1 1
Intro to Programming and Visual Basic .NET
Chapter 1
Chapter 1 2
Program
Set of instructions a computer follows to perform a task
Examples Calculate gross pay, taxes, and net pay Print past-due notices to credit card holders Drop the lowest homework assignment score
Chapter 1 3
Computer Programs
Used in most industries Accounting Human Resources Education Aviation Marketing
Chapter 1 4
Program Acquisition
Shrink-Wrap Software Very available Lower cost Standardized, not customizable
In-house Development Higher cost Customizable to specific needs
Outsourcing Higher cost Customizable
Chapter 1 5
Methods of Programming
Procedural Statements executed by the computer, one
after another, in sequential order from start to termination of a program
Typical of text-based terminal User responds to program
Object-Oriented GUI interface consisting of a set of objects Program responds to user
Chapter 1 6
Procedural Program Example
1. Display onscreen message: "How many hours did you work?"
2. Allow the user to enter the number of hours worked3. Once the user enters a number, store it in memory4. Display onscreen message: “What is your hourly
pay rate?"5. Allow the user to enter an hourly pay rate6. Once the user enters a number, store it in memory7. Multiply the two numbers stored in memory and
store the result in memory8. Display a message on the screen that shows the
gross pay. The message must include the result of the calculation performed in step 7
Chapter 1 7
Procedural Program Example
How many hours did you work? 10
What is your hourly pay rate? 15
Your gross pay is $150.00
C>_
Chapter 1 8
Object-Oriented Programming (OOP)
Centered on object creation. Object: element containing data & actions
Examples Form (window) object Label (descriptions) object Text Box (data entry) object Button (event driven) object
Attributes (Properties) Text property (e.g., Hourly Pay Rate) Size (Height & Width) Location (Vertical & Horizontal Position)
Chapter 1 9
Event-Driven Programming
Responds to events Action or occurrence that takes place in the
program. User Action Examples
Click or double-click a button Press a key on the keyboard
System Occurrences Examples Timer
Sits idle until an event occurs—again program responds to user (or system).
Chapter 1 10
Events
Button Object (Control) responds to a Click event.
Text Box Object (Control) responds to data entry, which is a TextChanged event.
Chapter 1 11
Event Procedure
Algorithm that executes when the event occurs.
Not triggered until event occurs.
Chapter 1 12
Algorithm*
Formula or set of steps for solving a particular problem
Characteristics: Unambiguous Well-defined Clear Fewest steps possible Terminal
*Adapted from webopedia.com’s definition.
Chapter 1 13
Algorithm Example
*Example for algorithm definition on webopedia.com.
Chapter 1 14
Pseudocode*
Outline of a program No real formatting or syntax rules Cross between human language and
programming language. Human readable Basis for algorithm development No real programming language skills needed
*Adapted from webopedia.com’s definition and Gaddis’ definition.
Chapter 1 15
Pseudocode Example
Store hours worked from user input into memory
Store hourly pay rate from user input into memory
Multiply value of hours worked (in memory) by the hourly pay rate (in memory)*
Store result into memory Display result (in memory) as output
*Simple gross pay calculation ignoring overtime rates.
Chapter 1 16
Controls (Objects)
Control Prefix Example Description
Form frm frmMain GUI interface
Button btn btnClose Rectangular object that triggers event procedure when clicked
Label lbl lblGrossPay Box displaying text that user can’t change (descriptions & output)
Text txt txtPayRate Rectangular area for data input by user
Chapter 1 17
Control Prefixes (p. 9)
chk Check Box cbo Combo Box btn Button frm Form grp Group Box
lbl Label lst List Box mnu Menu rad Radio Button pic Picture Box txt Text Box
Chapter 1 18
Download Student Chapter 1 Files
Run Program2\bin\Program2.exe See p. 10
Chapter 1 19
Measures of Quality
Must fulfill users’ needs. Include required functionality. Perform functions correctly.
Should be easy to use with little training. Design for clarity.
Should be understandable looking at coding. Should have flexibility integrated for future
versions of application.
Chapter 1 20
System Development Life Cycle
Involves joint effort of users & programmers.
1. Identify user requirements.
2. Design the application.
3. Construct the application.
4. Implement the system.
Chapter 1 21
Step 1: Identify User Requirements
Review request forms from users. Communicate with users.
Identify current problems & concerns. Determine users’ needs:
Features Method of operation
Obtain contract if you are the outsource for another organization.
Chapter 1 22
Step 1, continued
Clearly define what the program should do.
Purpose To calculate the user’s gross pay.
Input # of hours worked
Hourly pay rate
Process Multiply # of hours worked by the hourly pay rate to obtain gross pay.
Output Display a message indicating the user’s gross pay.
Chapter 1 23
Step 2: Design (Plan) the Application
Create blueprint of application. Sketch components for each user interface,
similar to storyboarding.
Chapter 1 24
Step 2, continued
List needed controls (text boxes, labels, & buttons). Specify properties/attributes (Text) for each control. Specify methods/events (Click) for each control. Write pseudocode &/or flowchart Show design to users & obtain their feedback (very
critical). Revise design based on feedback and continue cycle
of user input.
Chapter 1 25
Step 2 (List Controls Needed)
Type Name DescriptionTextBox txtHoursWorked Allows the user to enter the number of hours worked.TextBox txtPayRate Allows the user to enter the hourly pay rateLabel lblGrossPay Displays the gross pay, after the btnCalcGrossPay
button has been clickedButton btnCalcGrossPay When clicked, multiplies the number of hours worked
by the hourly pay rateButton btnClose When clicked, terminates the application
Chapter 1 26
Step 2 (Define Control Property Values) Property—characteristic, such as control name Value—specific attribute, such as lblGrossPay
Control Type Control Name TextForm (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"
Chapter 1 27
Step 2 (List Methods for Controls)
Methods—specific actions to perform based on specific user action, such as mouse click
Method DescriptionbtnCalcGrossPay_Click Multiplies the number of hours worked by the
hourly pay rateThese values are entered into thetxtHoursWorked and txt-PayRate TextBoxesThe result is stored in the lblGrossPay Textproperty
btnClose_Click Terminates the application
Chapter 1 28
Step 2 (Write Pseudocode) Create a pseudocode version of each method:
Pseudocode is a combination of English and a programming language Critical to effect planning; saves valuable time when you start actual programming; minimizes errors as you program. For this application:
Store Number of Hours Worked times Hourly Pay Rate in grossPay.Store the value in grossPay in lblGrossPay.Text.
Chapter 1 29
Step 2 (Continued)
Check the code for errors: Go step by step through the code, running it in your
head as though the computer is running it. Keep track of where in the code is being executed. Keep track of the values of all of the variables.
Chapter 1 30
Begin Program
Input hourly rate
Input # of hours worked
Are the # of hours
> 40?
No
Multiply the hours worked by the hourly rate.
Yes
Multiply 40 by the hourly rate to get the regularly weekly pay.
Subtract 40 from the total hours worked to find the OT hours.
Multiply the pay rate by 1.5 to get the OT rate.
Multiply the OT hours by the OT rate to get the amount of OT pay.
Chapter 1 31
Multiply the hours worked by the hourly rate.
Multiply 40 by the hourly rate to get the regularly weekly pay.
Subtract 40 from the total hours worked to find the OT hours.
Multiply the pay rate by 1.5 to get the OT rate.
Multiply the OT hours by the OT rate to get the amount of OT pay.
Add the regular weekly pay and the OT pay.
Display gross pay
End Program
Chapter 1 32
Step 3: Construct the Application
Use VB to create the application. Create one piece (form) at a time.
Create form (user interface window) and set its properties.
Insert controls based on design specs. Set properties for all controls.
Write code for the event procedures. Use pseudocode to create event procedures
into correct syntax.
Chapter 1 33
Step 3 (continued)
Run the program. Test and debug the application throughout
development. Correct syntax errors, incorrect use of the language,
such as keyword. Correct logic errors, errors that don’t crash the
program but produce inaccurate results, such as adding instead of multiplying.
Use various examples of test data (different numbers, names, etc.).
Chapter 1 34
Getting Started
Create folder on H drive: ISYS1200 Create subfolders w/ in ISYS1200
Practice Assignments Slide Shows
Chapter 1 35
Visual Basic .NET Interface
Start program(see p. 22).
Specify folder and subfolder location (Location text box).
Type program name (Name text box). Chapter1GrossPay MulberyAssignment1
(for assignments)
Folder created within locationbased on project name typed
Chapter 1 36
Project
Numerous files to run program Keep in same folder; do not copy/paste
program files. Can copy/paste image files (bmp) into project
folder if need images
Chapter 1 37
Visual Basic .NET Environment
Mouseover tosee Toolbox
Form(interface)
Design window(displays form)
Form(s) withinSolution Explorer
Property windowfor selected object(currently the form)
Project name
Chapter 1 38
Design Window
Application’s forms Area where you design the interface Grid visible for programmer (not user)
Chapter 1 39
Solution Explorer Window
Solution (container for storing project files)
Chapter 1 40
Properties Window
Displays settings for currently selected object
Changes based on what is selected Currently shows properties for form
object Second example when a Label
control object is selected Note:
Some properties set at Design Time in Properties window.
Other properties set with programming code.
Chapter 1 41
Form Properties
Text Appears on title bar
StartPosition Form location onscreen WindowsDefault (default setting) CenterScreen (typical)
MaximizeBox and MinimizeBox True (Default) False (Dims or hides)
Icon Symbol in top left corner (left of Text property)
Chapter 1 42
ToolBox
Unpinned Pinned (stays onscreen)
Chapter 1 43
Textbook Reference
USE IT—YOU PAID FOR IT!!!! Read information (pp. 16-19). Complete tutorials (pp. 28-29). Answer Check Points (p. 34). Check answers in back of book (p. 819) Note key terms (pp. 36-37) Answer Review Questions (pp. 37-39).
Sometimes these make good test questions! Check answers from ftp site
