Catalog description: Introduction to computer programming together with the consideration of the impact of computers on society. Emphasis on logical problem-solving and algorithms. No credit given to students with credit for CS 151, CS 213 or Math 446, 471. Mode 2.
General description: This course is an introduction to the basic principles of computer programming. It focuses on developing problems solving skills through writing programs in Visual Basic 2008. Students learn to develop graphical user interfaces (GUI’s) and use basic programming language structures to develop algorithms for solving various kinds of problems.
Course objectives: Having completed this course successfully, the student should:
Projects and tests: There will be 5 programming projects and 4 tests (including the final). The due dates for the projects and tests are shown below in the schedule of classes. All projects must be submitted through the Vista course management system available through CentralPipeline (Student > Blackboard Vista Courses > CS-113) or directly at https://vista.csus.ct.edu/webct/logon/16588872290071
Grading: The final grade is based 50% on test grades and
50%
on project grades and will be affected by classroom participation,
conduct and attendance. The letter grade will be calculated according to
the following table:
| A | A- | B+ | B | B- | C+ | C | C- | D+ | D | D- | F |
| 95-100 | 90-94 | 87-89 | 84-86 | 80-83 | 77-79 | 74-76 | 70-73 | 67-69 | 64-66 | 60-63 | 0-59 |
Class Participation: Regular attendance and active class participation is expected from all students. If you must miss a class, try to inform the instructor of this in advance.
Unexcused late submission policy: Projects submitted more than two days after the due date will be graded one letter grade down. Projects submitted more than a week late will receive two letter grades down. No submissions will be accepted more than two weeks after the due date.
Honesty policy: It is expected that all students will conduct themselves in an honest manner (see the Academic Misconduct section), and NEVER claim work which is not their own. Violating this policy will result in a substantial grade penalty, and may lead to expulsion from the University. However, students are allowed to discuss projects with others and receive debugging help from others.
Academic Misconduct: All students are expected to demonstrate
integrity in the completion of their coursework. Academic integrity means
doing one's own work and giving proper credit to the work and ideas of
others. It is the responsibility of each student to become familiar with
what constitutes academic dishonesty and plagiarism and to avoid all forms
of cheating and plagiarism. Students who engage in plagiarism and other
forms of academic misconduct will face academic and possibly disciplinary
consequences. Academic sanctions can range from a reduced grade for the
assignment to a failing grade for the course. From a disciplinary standpoint,
an Academic Misconduct Report may be filed and a Faculty Hearing Board
may impose sanctions such as probation, suspension or expulsion. You may
find the full Academic Misconduct Policy online at http://web.ccsu.edu/academicintegrity/UndergradAcadMisconductPolicy.htm.
Please read it carefully.
Problem 2: Write a program that reads the temperature in Fahrenheit and prints the result in Celsius. Using variables, assignment, input and output.
Public Class Form1
Private Sub Form1_Click(ByVal sender As Object,
ByVal e As System.EventArgs) Handles Me.Click
Dim F, C As Integer
F = InputBox("Enter
the temperature in Fahrenheit")
C = 5 * (F - 32) / 9
lstBox.Items.Add(CStr(F)
& " Fahrenheit is eqivalent to " & CStr(C) & " Celsius")
End Sub
End Class
Problem 3: Write a program to print a table with Fahrenheit temperatures and their Celsius equivalent. Using repetition (loops).
0 –18
20 –7
40 4
60 16
...
300 149
Public Class Form1
Private Sub Form1_Click(ByVal sender As Object,
ByVal e As System.EventArgs) Handles Me.Click
Dim F, C As Integer
F = 0
Do While F <= 300
C = 5 * (F - 32) / 9
lstBox.Items.Add(CStr(F) & Chr(9) & CStr(C))
F = F + 20
Loop
End Sub
End Class
End Class
Private Sub Form1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Click
End Sub
End Class
Private Sub Form1_Click(ByVal sender As Object,
ByVal e As System.EventArgs) Handles Me.Click
MsgBox("Hello World")
End Sub
End Class
Private Sub btnClearInput_Click(ByVal sender
As System.Object, ByVal e As System.EventArgs) Handles btnClearInput.Click
txtInput.Clear()
End Sub
Private Sub btnClearOutput_Click(ByVal sender
As System.Object, ByVal e As System.EventArgs) Handles btnClearOutput.Click
txtOutput.Clear()
End Sub
Private Sub btnCopy_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnCopy.Click
txtOutput.Text = txtInput.Text
' txtOutput.AppendText(txtInput.Text
& Chr(10)) ' Use this statement for Multiline TextBox
End Sub
End Class
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
txtResult.Text = Val(txtInput1.Text)
+ Val(txtInput2.Text)
End Sub
Private Sub btnConcatenate_Click(ByVal sender
As System.Object, ByVal e As System.EventArgs) Handles btnConcatenate.Click
txtResult.Text = txtInput1.Text
& txtInput2.Text ' & may be replaced with +
End Sub
End Class
Example 2: Using variables: Option Explicit, assignments, conversions, widening and narrowing, Option Strict\
Option Explicit Off
Public Class Form1
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
X = txtInput1.Text
Y = txtInput2.Text
Result = X + Y
txtResult.Text = Result
End Sub
End Class
Public Class Form1
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
Dim Result As Integer,
X As Double, Y As Integer
X = CDbl(txtInput1.Text)
Y = CInt(txtInput2.Text)
Result = CInt(X + Y)
txtResult.Text = CStr(Result)
End Sub
End Class
Example 3: Scope of variables, class-level variables. Compare the programs below and explain the results.
Program #1:
Public Class Form1
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
txtResult.Text = Val(txtResult.Text)
+ Val(txtInput1.Text)
End Sub
End Class
Program #2:
Public Class Form1
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
Dim Sum As Integer
Sum = Sum + Val(txtInput1.Text)
txtResult.Text = Sum
End Sub
End Class
Program #3:
Public Class Form1
Dim Sum As Integer
Private Sub btnAdd_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnAdd.Click
Sum = Sum + Val(txtInput1.Text)
txtResult.Text = Sum
End Sub
End Class
Problem: Calculation of age (years and months lived) based on month and year of birth (Current month is 2, year - 2011, MOB is 3, YOB is 1956). Formula ("\" is integer division, "Mod" returns the remainder from integer division):
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
txtYears.Text = "Years
= " & CStr((2 + 2011 * 12 - 3 - 1956 * 12) \ 12)
txtMonths.Text = "Months
= " & CStr((2 + 2011 * 12 - 3 - 1956 * 12) Mod 12)
End Sub
Solution 2: Using variables and named constants - the Dim statement.
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim MOB, YOB, Months,
Years, MonthsLived As Integer
Const CurrentMonth As
Integer = 2
Const CurrentYear As
Integer = 2011
MOB = 3
' Set up the value for MOB
YOB = 1956
' Set up the value for YOB
MonthsLived = CurrentMonth
+ CurrentYear * 12 - MOB - YOB * 12
Months = MonthsLived
Mod 12 ' Remainder from integer division
Years = MonthsLived
\ 12 ' Integer division
txtYears.Text = "Years
= " & Years
txtMonths.Text = "Months
= " & Months
End Sub
Solution 3: Using input boxes to enter data. Replace the
constants 3 and 1956 with input boxes. Why do we need the CInt function?
...
MOB = CInt(InputBox("Enter
Month of Birth"))
YOB = CInt(InputBox("Enter
Year of Birth"))
...
Solution 4: Elaborating the interface - text boxes for
input, one-line output. Why do we need the CInt and CStr functions?
...
MOB = CInt(txtMOB.Text)
YOB = CInt(txtYOB.Text)
...
txtOutput.Text = " You
are " & CStr(Years) & " years and " & CStr(Months) & "
months old"
...
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As Integer
X = CInt(txtX.Text)
txtOutput1.Text = CStr(X)
& " > 5 = " & CStr(X > 5)
txtOutput2.Text = CStr(X)
& " < 10 = " & CStr(X < 10)
txtOutput3.Text = CStr(X)
& " > 5 And " & CStr(X) & " < 10 = " & CStr(X > 5 And
X < 10)
End Sub
Example 2: Check if X does not belong to the interval (5,10)
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
txtOutput.Text = CStr(IsNumeric(txtInput.Text))
End Sub
Example 3: Add or concatenate inputs depending on their type. Use If-Then block.
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
If IsNumeric(txtInput.Text)
= True Then
txtOutput.Text = CStr(Val(txtInput.Text) + Val(txtInput.Text))
End If
If IsNumeric(txtInput.Text)
= False Then
txtOutput.Text = txtInput.Text & txtInput.Text
End If
End Sub
Example 4: Boolean variables.
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim Num As Boolean
Num = IsNumeric(txtInput.Text)
If Num = True Then
txtOutput.Text = CStr(Val(txtInput.Text) + Val(txtInput.Text))
End If
If Num = False Then
txtOutput.Text = txtInput.Text & txtInput.Text
End If
End Sub
Example 5: If-Then-Else block (Num may be used instead of Num=true)
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal
e As System.EventArgs) Handles btnStart.Click
Dim Num As Boolean
Num = IsNumeric(txtInput.Text)
If Num = True Then
txtOutput.Text = CStr(Val(txtInput.Text) + Val(txtInput.Text))
Else
txtOutput.Text = txtInput.Text & txtInput.Text
End If
End Sub
Elaboration: Add or concatenate two items (add if both are numeric, otherwise concatenate).I
Problem 1: Calculation of age based on month and year of birth
Solution 1: No input data validation (see TOP 25 Most Dangerous Programming Errors)
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim MOB, YOB, Months,
Years, MonthsLived As Integer
Const CurrentMonth As
Integer = 9
Const CurrentYear As
Integer = 2010
MOB = CInt(InputBox("Enter
Month of Birth"))
YOB = CInt(InputBox("Enter
Year of Birth"))
MonthsLived = CurrentMonth
+ CurrentYear * 12 - MOB - YOB * 12
Months = MonthsLived
Mod 12 ' Remainder from integer division
Years = MonthsLived
\ 12 ' Integer division
txtOutput.Text = " You
are " & CStr(Years) & " years and " & CStr(Months) & "
months old"
End Sub
Solution 2: Data validation
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim MOB, YOB, Months,
Years, MonthsLived As Integer
Const CurrentMonth As
Integer = 9
Const CurrentYear As
Integer = 2010
MOB = CInt(InputBox("Enter
Month of Birth"))
YOB = CInt(InputBox("Enter
Year of Birth"))
If YOB > 2010 Or YOB
< 1900 Then ' Check
if YOB is out of the interval [1900,2010]
MsgBox(CStr(YOB) & " - Wrong year")
Else
MonthsLived = CurrentMonth + CurrentYear * 12 - MOB - YOB * 12
Months = MonthsLived Mod 12 ' Remainder from integer division
Years = MonthsLived \ 12 ' Integer division
txtOutput.Text = " You are " & CStr(Years) & " years and " &
CStr(Months) & " months old"
End If
End Sub
Solution 3: More elaborated verification - ElseIf clause.
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim MOB, YOB, Months,
Years, MonthsLived As Integer
Const CurrentMonth As
Integer = 9
Const CurrentYear As
Integer = 2010
MOB = CInt(InputBox("Enter
Month of Birth"))
YOB = CInt(InputBox("Enter
Year of Birth"))
If YOB > 2010 Or YOB
< 1900 Then ' Check
if YOB is out of the interval [1900,2010]
MsgBox(CStr(YOB) & " - Wrong Year")
ElseIf MOB > 12 Or MOB
< 1 Then ' Check
if MOB is out of the interval [1,12]
MsgBox(CStr(MOB) & " - Wrong Month")
Else
MonthsLived = CurrentMonth + CurrentYear * 12 - MOB - YOB * 12
Months = MonthsLived Mod 12 ' Remainder from integer division
Years = MonthsLived \ 12 ' Integer division
txtOutput.Text = " You are " & CStr(Years) & " years and " &
CStr(Months) & " months old"
End If
End Sub
Exercises:
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Const S As String =
"one two threefour five six "
Dim Pos As Integer
Pos = CInt(Rnd() * 5)
* 5
txtOutput.Text = S.Substring(Pos,
5)
End Sub
Example 7: Enter a number as a word (one, two, three, four, five, six) and print its numeric equivalent (1, 2, 3, 4, 5, 6). What happens if the input is not from the list?
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Const S As String =
"one two threefour five six "
Dim Pos, Num As Integer
Pos = S.IndexOf(txtInput.Text)
Num = (Pos \ 5) + 1
txtOutput.Text = CStr(Num)
End Sub
Solution 1: Using If-Then-ElseIf structures
Public Class Form1
Private Sub btnCalc_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnCalc.Click
Dim X, Y As Double
Dim Op As String
X = Val(txtOperand1.Text)
Y = Val(txtOperand2.Text)
Op = txtOperation.Text
If Op = "+" Then
txtResult.Text = CStr(X + Y)
ElseIf Op = "-" Then
txtResult.Text = CStr(X - Y)
ElseIf Op = "*" Then
txtResult.Text = CStr(X * Y)
ElseIf Op = "/" Then
If Y <> 0 Then
txtResult.Text = CStr(X / Y)
Else
txtResult.Text = "Division by 0"
End If
ElseIf Op = "\" Then
If Y <> 0 Then
txtResult.Text = CStr(X \ Y)
Else
txtResult.Text = "Division by 0"
End If
ElseIf Op = "mod" Then
txtResult.Text = CStr(X Mod Y)
Else
txtResult.Text = "Incorrect operation"
End If
End Sub
End Class
Solution 2: Using Select Case structures
Public Class Form1
Private Sub btnCalc_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnCalc.Click
Dim X, Y As Double
Dim Op As String
X = Val(txtOperand1.Text)
Y = Val(txtOperand2.Text)
Op = txtOperation.Text
Select Op
Case "+"
txtResult.Text = CStr(X + Y)
Case "-"
txtResult.Text = CStr(X - Y)
Case "*"
txtResult.Text = CStr(X * Y)
Case "/"
If Y <> 0 Then
txtResult.Text = CStr(X / Y)
Else
txtResult.Text = "Division by 0"
End If
Case "\"
If Y <> 0 Then
txtResult.Text = CStr(X \ Y)
Else
txtResult.Text = "Division by 0"
End If
Case "mod"
txtResult.Text = CStr(X Mod Y)
Case Else
txtResult.Text = "Incorrect operation"
End Select
End Sub
End Class
Exercises:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Total, Average
As Double
Dim N, Count As Integer
N = InputBox("How many
numbers?")
Count = 0
Total = 0
Do While Count <
N
X = Val(InputBox("Enter a number"))
Count = Count + 1
Total = Total + X
Loop
Average = Total / Count
txtOutput1.Text = "You
entered " & Count & " numbers totaling " & Total
txtOutput2.Text = "The
average of these numbers is " & Average
End Sub
End Class
Example 2: Print Fahrenheit to Celsius conversion table for 0, 10, 20, ..., 90, 100. Using a fixed-count loop - the number of repetitions is known in advance. The stopping condition is based on a counter or accumulator. Elaboration: Change the step (S), use Double instead of Integer.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Const F0 As Integer
= 0
Const F1 As Integer
= 100
Const S As Integer =
10
Dim F, C As Integer
F = F0
lstOutput.Items.Add("Fahrenheit"
& Chr(9) & "Celsius")
Do While F <= F1
C = (F - 32) * 5 / 9
lstOutput.Items.Add(CStr(F) & Chr(9) & Chr(9) & CStr(C))
F = F + S
Loop
End Sub
End Class
Example 3: Calculating Greatest Common Divisor (GCD) of
two integers - Euclid's algorithm. See an applet implementation of Euclid
here.
More about Euclid can be found here.
Using a variable-condition loop - the number of repetitions is NOT
known in advance.
Public Class Form1
Private Sub btnGCD_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnGCD.Click
Dim A, B As Integer
Dim X, Y, T As Integer
A = Val(txtVal1.Text)
B = Val(txtVal2.Text)
X = A
Y = B
Do While Y > 0
T = X Mod Y
X = Y
Y = T
Loop
txtOutput.Text = "The
GCD of " & CStr(A) & " and " & CStr(B) & " is " & CStr(X)
End Sub
End Class
Exercises:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim Number, Guess, Count
As Integer
Number = Second(Now())
Mod 11 ' Generate an unknown number using current
time
Count = 0
Do
Guess = InputBox("Enter a number between 0 and 10")
Count = Count + 1
If Guess > Number Then MsgBox("It's smaller")
If Guess < Number Then MsgBox("It's bigger")
If Guess = Number Then MsgBox("OK, the number is " & Number)
Loop While Guess <>
Number ' Until Guess = Number
MsgBox(Count & "
tries")
End Sub
End Class
Example 2: Counting, totaling, averaging a sequence of numbers. Exit the loop using a sentinel value.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim Number, Total, Average
As Double
Dim Count As Integer
Count = 0
Total = 0
Do
Number = InputBox("Enter a number (0 to exit)")
If Number <> 0 Then
Count = Count + 1
Total = Total + Number
End If
Loop While Number <>
0 ' Until Number = 0
Average = Total / Count
MsgBox("You entered
" & Count & " numbers totaling " & Total)
MsgBox("The average
of these numbers is " & Average)
End Sub
End Class
Example 3: Counting, totaling, averaging a sequence of numbers. Exit the loop using a sentinel value and a flag.
Problem 1: Calculating PI by approximation of the circle area (Monte Carlo method)
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y As Double
Dim I, N, M As Long
N = InputBox("How many
iterations?")
M = 0
For I = 1 To N
X = Rnd(1)
Y = Rnd(1)
If X * X + Y * Y < 1 Then M = M + 1
Next I
MsgBox("PI = " &
4 * M / N)
End Sub
End Class
Nested Loops
Problem 2: Print a table of approximation of PI
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y As Double
Dim I, N, M, Max As
Long
Max = InputBox("Max
number of iterations?")
lstOutput.Items.Add("Iterations"
& Chr(9) & "PI")
N = 1
Do
M = 0
For I = 1 To N
X = Rnd(1)
Y = Rnd(1)
If X * X + Y * Y < 1 Then M = M + 1
Next I
lstOutput.Items.Add(N & Chr(9) & 4 * M / N)
N = N * 2
Loop Until N >= Max
End Sub
End Class
Problem 3: . Print the proper factors of a number (the divisors except the number itself). If the number of proper factors is 1, then this is a prime number. Count the prime numbers less than a given number.
'Print the proper factors of a number
'and count the number of primes less than 20
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N, F, Fcount, P
As Integer, Line As String
P = 0
For N = 1 To 20
Line = CStr(N) & " "
Fcount = 0
For F = 1 To N / 2
If N Mod F = 0 Then
Line = Line & F & " "
Fcount = Fcount + 1
End If
Next F
If Fcount = 1 Then P = P + 1
lstOutput.Items.Add(Line)
Next N
lstOutput.Items.Add("Number
of primes = " & P)
End Sub
End Class
Problem 4: Tabulate Pi(N) using the "Brute force" approach. Pi(N) is the number of prime numbers less than or equal to N. For more information about prime numbers see this link.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N, F, Fcount, P
As Integer
P = 0
lstOutput.Items.Add("N"
& Chr(9) & "Pi(N)")
For N = 1 To 1000
Fcount = 0
For F = 1 To N / 2
If N Mod F = 0 Then Fcount = Fcount + 1
Next F
If Fcount = 1 Then P = P + 1
If N Mod 100 = 0 Then lstOutput.Items.Add(N & Chr(9) & P)
Next N
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim A, B As Integer
Dim X, Y, T As Integer
A = Val(txtVal1.Text)
B = Val(txtVal2.Text)
X = A
Y = B
Do While Y > 0
T = X Mod Y
X = Y
Y = T
Loop
txtOutput.Text = "The
GCD of " & CStr(A) & " and " & CStr(B) & " is " & CStr(X)
End Sub
End Class
2. Print the GCD of two numbers. Use a Sub procedure to print the GCD
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim A, B As Integer
A = Val(InputBox("Enter
first number"))
B = Val(InputBox("Enter
second number"))
txtOutput.Text = "The
GCD of " & CStr(A) & " and " & CStr(B) & " is "
Call GCD(A, B)
End Sub
Private Sub GCD(ByVal X As Integer, ByVal Y
As Integer)
Dim T As Integer
Do While Y > 0
T = X Mod Y
X = Y
Y = T
Loop
txtOutput.Text = txtOutput.Text
& CStr(X)
End Sub
End Class
3. Print the GCD of two numbers. Use a Sub procedure to calculate the GCD and a class-level variable to return the result.
Public Class Form1
Dim F As Integer ' Class-level (global) variable
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim A, B As Integer
A = Val(InputBox("Enter
first number"))
B = Val(InputBox("Enter
second number"))
Call GCD(A, B)
txtOutput.Text = "The
GCD of " & CStr(A) & " and " & CStr(B) & " is " & CStr(F)
End Sub
Private Sub GCD(ByVal X As Integer, ByVal Y
As Integer)
Dim T As Integer
Do While Y > 0
T = X Mod Y
X = Y
Y = T
Loop
F = X
End Sub
End Class
4. Add two fractions and simplify the result by using GCD
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N
For N = 1 To 20
Call PrintFactors(N)
Next N
End Sub
Private Sub PrintFactors(ByVal N As Integer)
Dim F As Integer, Line
As String
Line = CStr(N) &
" "
For F = 1 To N / 2
If N Mod F = 0 Then
Line = Line & F & " "
End If
Next F
lstOutput.Items.Add(Line)
End Sub
End Class
6. Use a form-level variable to return the number of proper factors
Public Class Form1
Dim Fcount As Integer
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N As Integer
For N = 1 To 10
Call Factors(N)
lstOutput.Items.Add(N & Chr(9) & Fcount)
Next N
End Sub
Private Sub Factors(ByVal N As Integer)
Dim F As Integer
Fcount = 0
For F = 1 To N / 2
If N Mod F = 0 Then Fcount = Fcount + 1
Next F
End Sub
End Class
7. Write a general sub procedure that returns the sum of the proper
factors of a number. Then use it in a program to find if a number is deficient,
abundant
or perfect.
Solution 1: No sub procedures
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y, Z, M, Max
As Double
X = InputBox("X = ?")
Y = InputBox("Y = ?")
Z = InputBox("Z = ?")
If X > Y Then
M = X
Else
M = Y
End If
' M is the maximum of X and Y
If M > Z Then
Max = M
Else
Max = Z
End If
' Max is the maximum of M and Z
MsgBox("The maximum
of " & X & ", " & Y & " and " & Z & " is
" & Max)
End Sub
End Class
Solution 2: Using sub procedure and returning values through a global variable
Public Class Form1
Dim Max As Double ' A global variable accessible
from any procedure
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y, Z As Double
X = InputBox("X = ?")
Y = InputBox("Y = ?")
Z = InputBox("Z = ?")
Call Max2(X, Y)
' Max is the maximum of X and Y
Call Max2(Max, Z) '
Max is the maximum of Max and Z
MsgBox("The maximum
of " & X & ", " & Y & " and " & Z & " is
" & Max)
End Sub
Public Sub Max2(ByVal A As Double, ByVal B As
Double) ' Return maximum in global variable Max
If A > B Then
Max = A
Else
Max = B
End If
End Sub
End Class
Solution 3: Returning values through a parameter
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y, Z, Max As
Double
X = InputBox("X = ?")
Y = InputBox("Y = ?")
Z = InputBox("Z = ?")
Call Max2(X, Y, Max)
' Max is the maximum of X and Y
Call Max2(Max, Z, Max)
' Max is the maximum of Max and Z
MsgBox("The maximum
of " & X & ", " & Y & " and " & Z & " is
" & Max)
End Sub
Public Sub Max2(ByVal A As Double, ByVal B As
Double, ByRef Max As Double)
If A > B Then
Max = A
Else
Max = B
End If
End Sub
End Class
Solution 4: Using function procedure
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y, Z, M, Max
As Double
X = InputBox("X = ?")
Y = InputBox("Y = ?")
Z = InputBox("Z = ?")
M = Max2(X, Y)
' Max is the maximum of X and Y
Max = Max2(M, Z)
' Max is the maximum of Max and Z
MsgBox("The maximum
of " & X & ", " & Y & " and " & Z & " is
" & Max)
End Sub
Public Function Max2(ByVal A As Single, ByVal
B As Single) As Double ' Note that there is a type definition here
If A > B Then
Max2 = A
Else
Max2 = B
End If
End Function
End Class
Elaboration: Using functions as parameters (modify the code above).
Solution 1: Using Call by Reference. If we enter 6 for A and 8 for B, the program prints: The GCD of 2 and 0 is 2 (Why?)
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim A, B, D As Integer
A = InputBox("A = ?")
B = InputBox("B = ?")
D = GCD(A, B)
MsgBox("The GCD of "
& A & " and " & B & " is " & D)
End Sub
Public Function GCD(ByRef X As Integer, ByRef
Y As Integer) As Integer
Dim R As Integer
Do While Y > 0
R = X Mod Y
X = Y
Y = R
Loop
GCD = X
End Function
End Class
Solution 2: Using Call by Value. Modify the function formal parameters as shown below. Then if we enter 6 for A and 8 for B, the program prints: The GCD of 6 and 8 is 2.
Public Function GCD(ByVal X As Integer, ByVal Y As Integer) As Integer
Dim R As Integer
Do While Y > 0
R = X Mod Y
X = Y
Y = R
Loop
GCD = X
End Function
Problem 2: Find and fix the bug in the following program (it always prints 0 as maximum).
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, Y, Z, Max As
Double
X = InputBox("X = ?")
Y = InputBox("Y = ?")
Z = InputBox("Z = ?")
Call Max2(X, Y, Max)
Call Max2(Max, Z, Max)
MsgBox("The maximum
of " & X & ", " & Y & " and " & Z & " is
" & Max)
End Sub
Public Sub Max2(ByVal A As Double, ByVal B As
Double, ByVal C As Double)
If A > B Then
C = A
Else
C = B
End If
End Sub
End Class
Problem 3: Add fractions and simplify the sum
' Compute A/B + C/D = Num/Den in rational numbers (fractions)
' Use GCD to simplify the sum
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim A, B, C, D, Num,
Den, F As Integer
A = InputBox("Enter
first numerator")
B = InputBox("Enter
first denominator")
C = InputBox("Enter
second numerator")
D = InputBox("Enter
second denominator")
Num = A * D + B * C
Den = B * D
F = GCD(Num, Den)
Num = Num / F
Den = Den / F
MsgBox(A & " / "
& B & " + " & C & " / " & D & " = " & Num &
"/" & Den)
End Sub
Public Function GCD(ByVal X As Integer, ByVal
Y As Integer) As Integer
Dim R As Integer
Do While Y > 0
R = X Mod Y
X = Y
Y = R
Loop
GCD = X
End Function
End Class
Problem 4: Modify the program from Problem 3 so that the simplificaiton is done by a subprocedure.
Problem 5: Modify the program from Problem 3 by adding subprocedures to add two fractions and divide two fractions..
Problem 2: Parsing a string of data: Given a sequence of words separated by blanks, the program prints each word on a separate line along with its type (sting or number). For example: given the string: "Name John Age 20" the program prints:
Name string
John string
Age string
20 number
Review of string built-in functions needed:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim Line As String,
W As String, N As Integer
Line = InputBox("Type
a line of text")
N = 0
Do
W = Word(Line)
If W <> "" Then
If IsNumeric(W) Then
MsgBox(W & " number")
Else
MsgBox(W & " string")
End If
N = N + 1
End If
Loop While W <> ""
MsgBox(N & " words")
End Sub
'Returns and removes the first word from S (S
is passed by reference, the function changes it).
Public Function Word(ByRef S As String) As String
Dim L As Integer, I
As Integer
S = LTrim(S)
' Trim the leading blanks (if any)
L = Len(S)
' L is the length of S
If L = 0 Then
' If no more charachters in S Then
Word = ""
' return empty string
Else
' Else (S is not empty) do the following:
I = InStr(S, " ")
' I = the position of the first blank
If I > 0 Then
' If I>0 (there is a blank in S) Then
Word = Mid(S, 1, I - 1) ' return the word before
the blank and
S = Mid(S, I, L - I + 1) ' remove it from S
Else
' Else (I=0, i.e. there is no blank after the word - last word is S)
Word = S
' Return the last word (i.e. S) and
S = ""
' remove it from S
End If
End If
End Function
End Class
Problem 2 elaboration: Count the number of strings and numbers and compute the average, min, and max for the numbers.
Problem 3: Write a program that reads student names and
their grades (0-100) specified on one line of text. Then it prints each
name and the corresponding letter grade on separate lines. Use the Word
function (above) to process the text input. The following table shows the
conversion between numeric and letter grades.
| A | B | C | D | F |
| 90-100 | 80-89 | 70-79 | 60-69 | 0-59 |
Private Sub Form_Click()
Print Fact(5) ' This should print 120
End Sub
Solution 1: Factorial (iterative)
Public Function Fact(N As Integer) As Integer
Dim F As Integer
F = 1
If N > 0 Then
Do While N > 0
F = F * N
N = N - 1
Loop
End If
Fact = F
End Function
Solution 2: Factorial (recursive)
Problem 2: Recursive procedure to draw a triangle (fractals)
Solution 1: Using triangles only
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles Button1.Click
Dim gr As Graphics =
picBox.CreateGraphics
Call triangle(gr, 10,
10, 500)
End Sub
Private Sub triangle(ByVal gr As Graphics, ByVal
X As Integer, ByVal Y As Integer, ByVal S As Integer)
If S = 1 Then
gr.DrawLine(Pens.Black, X, Y, X + 1, Y + 1)
Else
Call triangle(gr, X, Y, S / 2)
Call triangle(gr, X + S / 2, Y, S / 2)
Call triangle(gr, X, Y + S / 2, S / 2)
End If
End Sub
End Class
Solution 2: Using triangles and a square
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles Button1.Click
Dim gr As Graphics =
picBox.CreateGraphics
Call triangle(gr, 10,
10, 250)
End Sub
Private Sub square(ByVal gr As Graphics, ByVal
X As Integer, ByVal Y As Integer, ByVal S As Integer)
gr.DrawLine(Pens.Black,
X, Y, X, Y + S)
gr.DrawLine(Pens.Black,
X, Y + S, X + S, Y + S)
gr.DrawLine(Pens.Black,
X + S, Y + S, X + S, Y)
gr.DrawLine(Pens.Black,
X + S, Y, X, Y)
End Sub
Private Sub triangle(ByVal gr As Graphics, ByVal
X As Integer, ByVal Y As Integer, ByVal S As Integer)
If S = 1 Then
gr.DrawLine(Pens.Black, X, Y, X + 1, Y + 1)
Else
Call square(gr, X, Y, S / 2)
Call triangle(gr, X + S / 2, Y, S / 2)
Call triangle(gr, X, Y + S / 2, S / 2)
End If
End Sub
End Class
Problem 3: Write a function procedure greater(S1, S2) for comparing strings (lexicographic order). Examples:
greater("abc", "bbc") = True
greater("bbc", "abc") = False
greater("abc", "ab") = True
greater("abc", "abb") = True
Private Sub Form_Click()
Dim S1 As String, S2 As String
S1 = InputBox("Enter string")
S2 = InputBox("Enter another string")
Print S1;" is greater than "; S2, greater(S1,S2)
End Sub
Solution 1 (non-recursive):
Public Function greater(X As String, Y As String) As Boolean
Dim M As Integer, N As Integer, I As Integer
M = Len(X)
N = Len(Y)
I = 1
Do While I <= M And I <= N And Mid(X, I, 1) = Mid(Y,
I, 1)
I = I + 1
Loop
If I > M Then
greater = False
ElseIf I > N Then
greater = True
Else
greater = Asc(Mid(X, I, 1)) > Asc(Mid(Y, I,
1))
End If
End Function
Solution 2 (recursive):
Public Function greater(X As String, Y As String) As Boolean
If X = "" Then
greater = False
ElseIf Y = "" Then
greater = True
ElseIf Mid(X, 1, 1) <> Mid(Y, 1, 1) Then
greater = Asc(Mid(X, 1, 1)) > Asc(Mid(Y,
1, 1))
Else
X = Mid(X, 2, Len(X) - 1)
Y = Mid(Y, 2, Len(Y) - 1)
greater = greater(X, Y)
End If
End Function
File (text.txt) contents:
90 John SmithSolution 1: Read and print each line as a string
80 Al Clark
55 Sue Taylor
75 Ann Miller
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As String
Dim sr As IO.StreamReader
= IO.File.OpenText("data.txt")
Do While (sr.Peek <>
-1)
X
= sr.ReadLine
lstOutput.Items.Add(X)
Loop
End Sub
End Class
Solution 2: Read each line in two separate variables - Grade and Name.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As String, Grade
As Integer, Name As String
Dim sr As IO.StreamReader
= IO.File.OpenText("data.txt")
Do While (sr.Peek <>
-1)
X = sr.ReadLine
Grade = CInt(X.Substring(0, 2))
Name = X.Substring(3, X.Length - 3)
lstOutput.Items.Add(Grade & " " & Name)
Loop
End Sub
End Class
Elaborations:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X(10) As String,
N As Integer
Dim sr As IO.StreamReader
= IO.File.OpenText("data.txt")
N = 0
Do While (sr.Peek <>
-1)
X(N) = sr.ReadLine
N = N + 1
Loop
lstOutput.Items.Add(N
& " student records read")
For I = 0 To N - 1
lstOutput.Items.Add(X(I))
Next I
End Sub
End Class
Elaborations:
File contents:
90 John SmithA search for names with "A" must produce:
80 Al Clark
55 Sue Taylor
75 Ann Miller
80 Al ClarkSolution: Search the whole records (try searching by grade or part of it).
75 Ann Miller
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X(10) As String,
S As String, N As Integer
Dim sr As IO.StreamReader
= IO.File.OpenText("M:\data.txt")
N = 0
Do While (sr.Peek <>
-1)
X(N) = sr.ReadLine
N = N + 1
Loop
S = InputBox("Enter
student's record or part of it")
lstOutput.Items.Add("Student
records found:")
For I = 0 To N-1
If InStr(X(I), S) > 0 Then
lstOutput.Items.Add(X(I))
End
If
Next I
End Sub
End Class
Elaborations: Search by grades, grade intervals or by
letter grades (converted to intervals).
Public Class Form1
Dim Grade(10) As Integer
Dim N As Integer
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, P As String,
I As Integer
Dim sr As IO.StreamReader
= IO.File.OpenText("M:\data.txt")
N = 0
Do While (sr.Peek <>
-1)
X = sr.ReadLine
lstOutput.Items.Add(X)
Grade(N) = CInt(X.Substring(0, 2))
N = N + 1
Loop
P = "Unsorted: "
For I = 0 To N - 1
P = P & Grade(I) & " "
Next I
lstOutput.Items.Add(P)
Call SelectionSort()
P = "Sorted: "
For I = 0 To N - 1
P = P & Grade(I) & " "
Next I
lstOutput.Items.Add(P)
End Sub
Public Sub SelectionSort()
Dim I, J, T As Integer
For I = 0 To N - 1
J = MinIndex(I, N - 1)
T = Grade(I)
Grade(I) = Grade(J)
Grade(J) = T
Next I
End Sub
Public Function MinIndex(ByVal M As Integer,
ByVal N As Integer) As Integer
Dim Min, I As Integer
Min = Grade(M)
MinIndex = M
For I = M To N
If Grade(I) < Min Then
Min = Grade(I)
MinIndex = I
End If
Next I
End Function
End Class
2. Using Bubble Sort algortithm
Public Sub BubbleSort()
Dim I, Swaps, T As Integer
Do
Swaps = 0
For I = 0 To N - 2
If Grade(I) > Grade(I + 1) Then
T = Grade(I)
Grade(I) = Grade(I + 1)
Grade(I + 1) = T
Swaps = Swaps + 1
End If
Next
I
Loop While Swaps > 0
End Sub
Elaborations:
What happens if X and Y are both of type Double? What happens if Option
Strict is on?
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim R, H, V As Double
R = InputBox("Enter
Radius")
H = InputBox("Enter
Height")
If R > 0 And H > 0 Then
V = 3.141592 * R ^ 2 * H
MsgBox("Volume of the cylinder = " & V)
Else
MsgBox("Incorrect input. Try again")
End If
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N As Integer, S
As Double
N = InputBox("Enter
an integer number")
If N > 0 Then
S = Math.Sqrt(N)
If S = CInt(S) Then
MsgBox(N & " is a perfect square")
Else
MsgBox(N & " is not a perfect square")
End If
Else
MsgBox("Incorrect Input. Try agian")
End If
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim I As Integer, S
As Double
For I = 10 To 30
If I Mod 2 = 0 Then
lstOutput.Items.Add(I)
End If
Next I
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N, I, EvenCount,
OddCount As Integer
EvenCount = 0
OddCount = 0
For I = 1 To 10
N
= InputBox("Enter a number")
If N Mod 2 = 0 Then
EvenCount = EvenCount + 1
Else
OddCount = OddCount + 1
End If
Next I
lstOutput.Items.Add(EvenCount
& " even numbers")
lstOutput.Items.Add(OddCount
& " odd numbers")
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim I As Integer, S
As Single
S = 0
I = 0
Do
I = I + 1
S = S + 1 / I
Loop Until S > 10
MsgBox(I)
End Sub
End Class
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim I As Integer
For I = 1 To 100
If I Mod 3 = 0 Then
lstOutput.Items.Add(I)
End If
Next I
End Sub
End Class
Problem 2: Modify the program from Problem 1, so that it uses a Do-Loop-While structure.
Problem 3: Modify the following program, so that it stops when more than 10 numbers are entered. Use the same type of loop.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim N, EvenCount, OddCount
As Integer
EvenCount = 0
OddCount = 0
Do
N = InputBox("Enter a number")
If N Mod 2 = 0 Then
EvenCount = EvenCount + 1
Else
OddCount = OddCount + 1
End
If
Loop While N <> 0
lstOutput.Items.Add(EvenCount
& " even numbers")
lstOutput.Items.Add(OddCount
& " odd numbers")
End Sub
End Class
Problem 4: What does the program below print? Circle the correct answer and explain it.
a) 1.5 b) 2 c) 3 c) nothing (goes into infinite loop)Public Class Form1
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As Integer, Y As Integer
X = InputBox("Enter a number")
Y = InputBox("Enter another
number")
Call PrintMin(X, Y)
' Prints the smaller of X and Y
Call PrintMax(X, Y)
' Prints the bigger of X and Y
Call PrintAverage(X, Y) '
Prints the average of X and Y
End Sub
End Class
2. Use the follwing general sub procedure
Private Sub PrintAverage(X As Integer, Y As Integer, Z As Integer)
Dim Average As Double
Average = (X + Y + Z) / 3
MsgBox("The average is :" & Average)
End Sub
a) write a program to print the average of 1, 2, and 4.
b) write a program that inputs (with InputBox) 3 integers and prints
their average.
c) write a program that prints the average of 2.5, 3.14, and 7. Hint:
modify PrintAverage accordingly.
3. Do problem 2, however use class-level variables to pass the numbers to PrintAverage. That is, the sub procedure should be defined without parameters as follows:
Private Sub PrintAverage()
Dim Average As Double
Average = (X + Y + Z) / 3
MsgBox("The average is :" & Average)
End Sub
4. What does the program below print? 1 or 2? Explain why. What happens if ByVal is replaced with ByRef in AddOne?
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As Integer
X = 1
Call AddOne(X)
MsgBox(X)
End Sub
Private Sub AddOne(ByVal X As Integer)
X = X + 1
End Sub
End Class
5. Write function procedures to complete the program below:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As Integer, Y
As Integer
X = InputBox("Enter
a number")
Y = InputBox("Enter
another number")
MsgBox(Min(X, Y))
' Prints the smaller of X and Y
MsgBox(Max(X, Y))
' Prints the bigger of X and Y
MsgBox(Average(X, Y))
' Prints the average of X and Y
End Sub
End Class
6. Use the follwing function procedure
Private Function Average(X As Integer, Y As Integer, Z As Integer)
As Single
Average = (X + Y + Z) / 3
End Function
a) write a program to print the average of 1, 2, and 4.
b) write a program that inputs (with InputBox) 3 integers and prints
their average.
c) write a program that prints the average of 2.5, 3.14, and 7. Hint:
modify Average accordingly.
7. Write a sub proceduire and a function procedure to complete the program below:
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X As Integer, Y As Integer
Call InputTwoNumbers(X, Y)
' Reads two numbers from user input
MsgBox("The sum is " &
Sum(X, Y)) ' Print the sum of X and Y
End Sub
End Class
8. Use the follwing sub procedure
Private Sub Average(ByVal X As Integer, ByVal Y As Integer, ByVal
Z As Integer, ByRef W As Double)
W = (X + Y + Z) / 3
End Sub
a) write a program to print the average of 1, 2, and 4.
b) write a program that inputs (with InputBox) 3 integers and prints
their average.
c) write a program that prints the average of 2.5, 3.14, and 7. Hint:
modify Average accordingly.
The product of 2/5 and 3/4 is 6/20
The product of 2/5 and 3/4 is decimal is 0.3
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal
e As System.EventArgs) Handles btnStart.Click
Dim A, B, C, D As Integer
A = 2
B = 5
C = 3
D = 4
lstOutput.Items.Add(_____________________________________)
lstOutput.Items.Add(_____________________________________)
End Sub
Elaboration: Use TextBoxes to assign values to the variables A, B, C, and D.
Problem 2. Change the Do-While-Loop with a For-Next loop in the program below. The new program should produce exactly the same output as the original one.
Public Class Form1
Private Sub btnStart_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnStart.Click
Dim X, S, Y As Integer
S = 0
X = 1
Do While X <= 100
S = S + X
lstOutput.Items.Add(S)
X = X + 3
Loop
End Sub
End Class
Problem 3. Rewrite the following code without ElseIF. The new code should work exactly in the same way as the original one.
If T > 90 Then
MsgBox("Hot")
ElseIf T < 60 Then
MsgBox("Cold")
Else
MsgBox("Nice")
End If
Problem 4. Assume that variable X has the value of 1. Write next to each of the following conditions whether it is true or false.
a) X >= 1 AND X < 1
b) X < 4 OR X > 4
c) X = 1 AND X >= 1 AND X < 7
d) (X > 3 OR X <= 7) AND (X < 0 OR X >
0)
Problem 5. Describe all visual objects, procedures and functions used in the following program.
Public Class Form1
Private Sub btnStart_Click(...) Handles
btnStart.Click
Dim X, P As String,
I As Integer
Dim sr As IO.StreamReader
= IO.File.OpenText("M:\data.txt")
N = 0
Do While (sr.Peek <>
-1)
X = sr.ReadLine
lstOutput.Items.Add(X)
Grade(N) = CInt(X.Substring(0, 2))
N = N + 1
Loop
P = "Unsorted: "
For I = 0 To N - 1
P = P & Grade(I) & " "
Next I
lstOutput.Items.Add(P)
Call BubbleSort()
P = "Sorted: "
For I = 0 To N - 1
P = P & Grade(I) & " "
Next I
lstOutput.Items.Add(P)
End Sub
Public Sub BubbleSort()
Dim I, Swaps, T As Integer
Do
Swaps = 0
For I = 0 To N - 2
If Grade(I) > Grade(I + 1) Then
T = Grade(I)
Grade(I) = Grade(I + 1)
Grade(I + 1) = T
Swaps = Swaps + 1
End If
Next I
Loop While Swaps > 0
End Sub
End Class
Problem 6. Write a program that computes the sum of the following sequence of numbers: 1,4,7,10,…, 100. Use a loop.
Problem 7. A store sells CDs at 50 cents for small orders, at 40 cents for orders of 20 to 100, and at 30 cents for orders of more than 100. Write a program that requests the number of CD ordered and prints the total cost.
Problem 8. Complete the sub procedure below so that it prints the smallest of the four numbers passed as parameters.
Public Sub Min4(ByVal A As Double, ByVal B As Double, ByVal C As Double, ByVal D As Double)
End Sub
Problem 9. Write a program that reads 10 integers from user input
and prints every other one in a reverse order. Use an array.