meljun cortes technical faculty module part2 wsd
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Introduction to Computer Programming
MELJUN CORTESMELJUN CORTES
Visual Basic .Net Programming Using Visual Studio .Net
Objectives
This module aims:• To introduce the software development process;• To know the different programming constructs of
Visual Basic .NET; and• To enhance the programming skills of the
participants.
Topics
• The software development process
• Different Control Structures in programming
• Visual Basic .NET examples
• Lab Exercise
The Software Development Process
1. Problem Analysis
2. Setting up an algorithm
3. Implementing your algorithm
4. Running, Testing, & Debugging
5. Documentation
Problem!
Mr. De la Cruz needs a program to compute grades of 50 students. Grade computation is:
40% Average of 3 Exams
+ 40% Final Exam
20% Class participation
100%
Once grade of a student is computed the program also displays if student passed or failed. Passing grade is 70%.
1. What are we asked to do?
Compute the final grade, and
determine if student is passing or not
1. Problem analysis
2. What are the given data (inputs) and results that are to be produced (outputs)?
Input: Quiz No. 1 (Q1)
Quiz No. 2 (Q2) Quiz No. 3 (Q3) Final Exam (FE) Class Participation (CP)
Output: Final Grade (FG)
1. Problem analysis
3. How do we accomplish our task?
FG = 40%
+ 30% (FE)
+ 15% (CP)
Q1 + Q2 + Q3
3
1. Problem analysis
Algorithm a list or sequence of steps that solves the
given problemNote: The steps should be as detailed as
possible.
2. Set-up Algorithm
Example:Step 1. Get Q1, Q2, and Q3 gradeStep 2. Get FE gradeStep 3. Get CP gradeStep 4. Calculate the FG using the formulaStep 5. Display the final grade FG
Step 6. Determine if student passed or failedStep 7. If students processed < 50,
go back to step 1 and process next student.
2. Set-up Algorithm
Refining the algorithm
Step 6. Determine if student passed or failed
Step 6. Determine if student passed or failed
Step 6.1. If FG < 70%,
display student failed
otherwise,
display student passed
3. Implementing the algorithm
Basic Questions:1. How do you get input and display output?2. How do you store information?3. How do you write formula?4. How do you make a program perform statements
depending on different situations?5. How do you make a program repeat parts of itself?
Getting input and output
Using consoleImports System
Public Module Hello
Public Sub Main( )
Console.WriteLine("hello, world")
End Sub
End Module
Screen output
Getting input and output
Demo using GUI
How do we store data?
Answer: Use variables
Declaring variables:
Dim variable As datatype
Rules:1. Must begin with a character or underscore2. Cannot have special characters3. Cannot be a reserved word
Basic data types in VB .NET
Numerical:
Integer (whole numbers)
Float (floating point)
Non-numerical:
Boolean (true or false values)
Char (a single character)
String (many characters)
Sample Declaration
Dim finalGrade As Float
Dim quiz1 As Integer
Dim name As String
Programming Tips…
1. Use descriptive variable names2. Don’t use names that differ by only one character
ex. Dim final As Float Dim finals As Float
3. Use names that are not too long and not too short
Branching constructs
The If statement
Syntax 1: If expression Then
statements
End If
Example
For the problem of Mr. dela Cruz, to determine if a student passed or failed, we use:
If finalGrade >= 70 Then
Console.WriteLine(“Passed”)
End If
If finalGrade < 70 Then
Console.WriteLine(“Failed”)
End If
Branching constructs
The If statement
Syntax 2: If expression Then
statements
Else
statements
End If
Example
For the problem of Mr. dela Cruz, to determine if a student passed or failed, we use:
If finalGrade >= 70 Then
Console.WriteLine(“Passed”)
Else
Console.WriteLine(“Failed”)
End If
Branching constructs
The If statement
Syntax 3: If expression Thenstatements
ElseIf expression Thenstatements
ElseIf expression Thenstatements
Elsestatements
End If
Example
If finalGrade >= 90 Then
Console.WriteLine(“Very Good”)
ElseIf finalGrade >= 80 Then
Console.WriteLine(“Good”)
ElseIf finalGrade >= 70 Then
Console.WriteLine(“Satisfactory”)
Else
Console.WriteLine(“Needs Improvement”)
End If
Looping constructs
• Allow a group of statements to be executed more than once
• Looping statements in VB .NET:– Do– For– For Each
Looping constructs
The Do statement
Body of the loop is executed either:
1. while a condition remains true; or
2. until the condition becomes true
Looping constructs
The Do statement examples
Do While count < 50' statements
Loop
Do Until count > 50' statements
Loop
Do ' statementsLoop While count <= 50
Do ' statementsLoop Until count >= 50
Do ' statementsLoop
Looping constructs
The For statement
• Body of the loop is executed a fixed number of times
• Looping is controlled by a loop control variable
Looping constructs
Syntax of For statement:
For var = expr To expr [ Step expr ]
statements
Next [ variable_list ]
Looping constructs
Example of For statement:
For i = 1 To 10
Next
For i = 1 To 10
For j = 1 To 10
Next i, j
For i = 1 To 10
For j = 1 To 10
Next
Next
Different bugs or errors encountered:
• Syntactical errors are caused by deviating from grammatical rules of the language.
• Logical errors are caused due to faulty algorithm formulation
4. Run, Test, debug
Reasons for doing documentation:1. Ease of understanding different parts of the
code.2. Reduces efforts during program maintenance
and problem reconstruction.
Internal Documentation in VB .NET:‘ This is a comment
5. Documentation
.NET Hands On Exercises
Exercises
• Lab1: Flash Cards
• Lab2: XChange
• Lab3: Student Picker
• Lab4: Mine Sweeper
Flash Cards
• Objectives– Design a graphical user interface.– Modify the properties of the user controls.– Create and call functions.– Perform input and output operations.– Create and evaluate statements and
expressions.– Implement and analyze program branching.
Flash Cards
• Features– Generates random
algebra problems.– Checks user input if
correct or incorrect.– Optional: scoring
– Optional: hints
Flash Cards
• Creating the GUI– Drag and drop controls from the toolbox.– Use the properties window to modify the windows
controls.– Change the names of the controls.
Flash Cards
• Declaring Variables
Flash Cards
• Creating Functions
Flash Cards
• Generating the problem
Flash Cards
Flash Cards
Flash Cards
• Checking the answer
Flash Cards
• Giving hints
XChange
• Objectives– Modify the properties of the user controls.– Create and call functions.– Convert data types.– Create and evaluate statements and
expressions.– Handle Windows control events.
XChange
• Features– Converts one value to
another based on a given formula.
– Customizable conversion functions.
XChange
• Synchronize TrackBar and Label
XChange
• Convertion Functions
XChange
• Convert Left Value
XChange
• Convert Right Value
XChange
• Dollar to Peso Conversion
XChange
• Grade Equivalent of 70 pt Exam
XChange
• Other Applications– Celsius to Fahrenheit– Pounds to Kilos– Inches to Centimeters– Etc.
Teaching Assistant
• Objectives– Call functions and pass parameters– Practice looping constructs and conditions– Work with list controls– Use the features of collections– Handle file input and output
Teaching Assistant
• Features– Class attendance
checker– Random student
selection– Load/Save class lists
Teaching Assistant
• Adding new students
Teaching Assistant
• Deleting students
Teaching Assistant
• Checking class attendance
Teaching Assistant
• Checking class attendance
Teaching Assistant
• Checking class attendance
Teaching Assistant
• Create a random function
Teaching Assistant
• Randomly select a present student
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