|
Public Class Tester
Public Shared Sub Main
Dim result As New System.Text.StringBuilder
Dim testDouble As Double = Math.PI
result.Append("Double ").AppendLine(testDouble)
testDouble += Math.PI
result.Append("+= ").AppendLine(testDouble)
testDouble *= Math.PI
result.Append("*= ").AppendLine(testDouble)
testDouble -= Math.PI
result.Append("-= ").AppendLine(testDouble)
testDouble /= Math.PI
result.Append("/= ").AppendLine(testDouble)
testDouble ^= Math.PI
result.Append("^= ").AppendLine(testDouble)
result.AppendLine()
Dim testInteger As Integer = 17
result.Append("Integer ").AppendLine(testInteger)
testInteger \= 2
result.Append("\= 2 ... ").AppendLine(testInteger)
testInteger += 1
result.Append("+= 1 ... ").AppendLine(testInteger)
testInteger <<= 1
result.Append("<<= 1 ... ").AppendLine(testInteger)
testInteger >>= 3
result.Append(">>= 3 ... ").AppendLine(testInteger)
result.AppendLine()
Dim testString As String = "Abcdef"
result.Append("String ").AppendLine(testString)
testString &= "ghi"
result.Append("&= ghi ... ").AppendLine(testString)
testString += "jkl"
result.Append("+= jkl ... ").AppendLine(testString)
Console.WriteLine(result.ToString())
End Sub
End Class
|
3.1.2.Using an assignment operator to calculate a power of 2
|
Module Tester
Sub Main()
Dim exponent As Integer ' power input by user
Dim result As Integer = 2 ' number to raise to a power
exponent = 12
result ^= exponent ' same as result = result ^ exponent
Console.WriteLine("result = exponent: {0}", result)
result = 2 ' reset result to 2
result = result ^ exponent
Console.WriteLine("result = result exponent: {0}", result)
End Sub
End Module
|
result = result ^ exponent: 4096
|
' Quote from
'Visual Basic 2005 Cookbook Solutions for VB 2005 Programmers
'by Tim Patrick (Author), John Craig (Author)
'# Publisher: O'Reilly Media, Inc. (September 21, 2006)
'# Language: English
'# ISBN-10: 0596101775
'# ISBN-13: 978-0596101770
Public Class Tester
Public Shared Sub Main
Console.WriteLine(FindPi(500))
End Sub
Private Shared NumberDigits As Integer
Public Shared Function FindPi(ByVal digits As Integer) As String
' ----- Calculate Pi to the specified number of digits,
' based on the formula:
' Pi/4 = arctan(1/2) + arctan(1/3)
Dim result As New System.Text.StringBuilder("PI=3.")
Dim digitIndex As Integer
Dim divFactor As Integer
' ----- Build an array that will hold manual calculations.
NumberDigits = digits + 2
Dim targetValue(NumberDigits) As Integer
Dim sourceValue(NumberDigits) As Integer
' ---- Perform the calculation.
divFactor = 2
ArcTangent(targetValue, sourceValue, divFactor)
divFactor = 3
ArcTangent(targetValue, sourceValue, divFactor)
ArrayMult(targetValue, 4)
' ----- Return a string version of the calculation.
For digitIndex = 1 To NumberDigits - 3
result.Append(Chr(targetValue(digitIndex) + Asc("0"c)))
Next digitIndex
Return result.ToString
End Function
Private Shared Sub ArrayMult(ByRef baseNumber() As Integer, _
ByRef multiplier As Integer)
' ----- Multiply an array number by another number by hand.
' The product remains in the array number.
Dim carry As Integer
Dim position As Integer
Dim holdDigit As Integer
' ----- Multiple each base digit, from right to left.
For position = NumberDigits To 0 Step -1
' ----- If the multiplication went past 9, carry the
' tens value to the next column.
holdDigit = (baseNumber(position) * multiplier) + carry
carry = holdDigit \ 10
baseNumber(position) = holdDigit Mod 10
Next position
End Sub
Private Shared Sub ArrayDivide(ByRef dividend() As Integer, ByRef divisor As Integer)
' ----- Divide an array number by another number by hand.
' The quotient remains in the array number.
Dim borrow As Integer
Dim position As Integer
Dim holdDigit As Integer
' ----- Process division for each digit.
For position = 0 To NumberDigits
' ----- If the division can't happen directly, borrow from
' the previous position.
holdDigit = dividend(position) + borrow * 10
dividend(position) = holdDigit \ divisor
borrow = holdDigit Mod divisor
Next position
End Sub
Private Shared Sub ArrayAdd(ByRef baseNumber() As Integer, ByRef addend() As Integer)
' ----- Add two array numbers together.
' The sum remains in the first array number.
Dim carry As Integer
Dim position As Integer
Dim holdDigit As Integer
' ----- Add each digit from right to left.
For position = NumberDigits To 0 Step -1
' ----- If the sum goes beyond 9, carry the tens
' value to the next column.
holdDigit = baseNumber(position) + addend(position) + carry
carry = holdDigit \ 10
baseNumber(position) = holdDigit Mod 10
Next position
End Sub
Private Shared Sub ArraySub(ByRef minuend() As Integer, ByRef subtrahend() As Integer)
' ----- Subtract one array number from another.
' The difference remains in the first array number.
Dim borrow As Integer
Dim position As Integer
Dim holdDigit As Integer
' ---- Subtract the digits from right to left.
For position = NumberDigits To 0 Step -1
' ----- If the subtraction would give a negative value
' for a column, we will have to borrow.
holdDigit = minuend(position) - subtrahend(position) + 10
borrow = holdDigit \ 10
minuend(position) = holdDigit Mod 10
If (borrow = 0) Then minuend(position - 1) -= 1
Next position
End Sub
Private Shared Function ArrayZero(ByRef baseNumber() As Integer) As Boolean
' ----- Report whether an array number is all zero.
Dim position As Integer
' ----- Examine each digit.
For position = 0 To NumberDigits
If (baseNumber(position) <> 0) Then
' ----- The number is nonzero.
Return False
End If
Next position
' ----- The number is zero.
Return True
End Function
Private Shared Sub ArcTangent(ByRef targetValue() As Integer, _
ByRef sourceValue() As Integer, _
ByVal divFactor As Integer)
' ----- Calculate an arctangent of a fraction, 1/divFactor.
' This routine performs a modified Maclaurin series to
' calculate the arctangent. The base formula is:
' arctan(x) = x - x^3/3 + x^5/5 - x^7/7 + x^9/9 - ...
' where -1 < x < 1 (it's 1/divFactor in this case).
Dim workingFactor As Integer
Dim incremental As Integer
' ----- Figure out the "x" part, 1/divFactor.
sourceValue(0) = 1
incremental = 1
workingFactor = divFactor
ArrayDivide(sourceValue, workingFactor)
' ----- Add "x" to the total.
ArrayAdd(targetValue, sourceValue)
Do
' ----- Perform the "- (xy)/y" part.
ArrayMult(sourceValue, incremental)
workingFactor = divFactor * divFactor
ArrayDivide(sourceValue, workingFactor)
incremental += 2
workingFactor = incremental
ArrayDivide(sourceValue, workingFactor)
ArraySub(targetValue, sourceValue)
' ----- Perform the "+ (xy)/y" part.
ArrayMult(sourceValue, incremental)
workingFactor = divFactor * divFactor
ArrayDivide(sourceValue, workingFactor)
incremental += 2
workingFactor = incremental
ArrayDivide(sourceValue, workingFactor)
ArrayAdd(targetValue, sourceValue)
Loop Until ArrayZero(sourceValue)
End Sub
End Class
|
PI=3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211
7067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930
3819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491
4127372458700660631558817488152092096282925409171536436789259036001133053054882046652138414695194151
1609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011
3.1.4.Prime numbers using the Sieve of Eratosthenes
|
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Collections
Public Class Tester
Public Shared Sub Main
Dim needBreak As Boolean = True
Console.WriteLine("Prime numbers using the ""Sieve of Eratosthenes""")
Dim index As Integer = 1
Dim counter As Integer
Do While (index < (MaxNumber - 1))
index += 1
If (PrimeStorage(index) = True) Then
For counter = index * 2 To MaxNumber - 1 Step index
PrimeStorage(counter) = False
Next counter
End If
Loop
For counter = 2 To 7999999
If (GetBit(counter) = 1) Then
If (counter < 50) Or (counter > 7999800) Then
Console.WriteLine(counter)
ElseIf (needBreak = True) Then
Console.WriteLine("...")
needBreak = False
End If
End If
Next counter
End Sub
Private Const MaxNumber As Integer = 8000000
Private Shared PrimeStorage As New BitArray(MaxNumber, True)
Public Shared Function GetBit(ByVal index As Integer) As Integer
If (PrimeStorage(index) = True) Then Return 1 Else Return 0
End Function
End Class
|
Prime numbers using the "Sieve of Eratosthenes
3.2.1.Shortcut assignment operators
|
Module Tester
Sub Main()
Dim A As Integer
A = 0
A += 10
Console.WriteLine("A += 10 yields " & A)
A -= 5
Console.WriteLine("A -=5 yields " & A)
A *= 3
Console.WriteLine("A *= 3 yields " & A)
A /= 5
Console.WriteLine("A /= 5 yields " & A)
A ^= 2
Console.WriteLine("A = 2 yields " & A)
End Sub
End Module
|
|
Option Strict On
Imports System
Module Module1
Sub Main( )
Dim value As Integer = 5
Dim power As Integer = 4
Console.WriteLine("{0} to the {1}th power is {2}", _
value, power, value ^ power)
End Sub
End Module
|
5 to the 4th power is 625
3.2.3.Boolean value with And and Or
|
Option Strict On
Imports System
Module Module1
Sub Main( )
Dim x As Integer = 5
Dim y As Integer = 7
Dim andValue As Boolean
Dim orValue As Boolean
Dim xorValue As Boolean
Dim notValue As Boolean
andValue = x = 3 And y = 7
orValue = x = 3 Or y = 7
xorValue = x = 3 Xor y = 7
notValue = Not x = 3
Console.WriteLine("x = 3 And y = 7. {0}", andValue)
Console.WriteLine("x = 3 Or y = 7. {0}", orValue)
Console.WriteLine("x = 3 Xor y = 7. {0}", xorValue)
Console.WriteLine("Not x = 3. {0}", notValue)
End Sub 'Main
End Module
|
3.3.1.Logical operator: AndAlso
|
Module Tester
Sub Main()
Console.WriteLine("AndAlso" & vbCrLf & vbCrLf & _
"False AndAlso False: " & (False AndAlso False) & _
vbCrLf & "False AndAlso True: " & _
(False AndAlso True) & vbCrLf & _
"True AndAlso False: " & (True AndAlso False) & _
vbCrLf & "True AndAlso True: " & (True AndAlso True))
End Sub
End Module
|
False AndAlso False: False
False AndAlso True: False
True AndAlso False: False
3.3.2.Logical operator: OrElse
|
Module Tester
Sub Main()
Console.WriteLine("OrElse" & vbCrLf & vbCrLf & _
"False OrElse False: " & (False OrElse False) & _
vbCrLf & "False OrElse True: " & (False OrElse True) & _
vbCrLf & "True OrElse False: " & (True OrElse False) & _
vbCrLf & "True OrElse True: " & (True OrElse True))
End Sub
End Module
|
False OrElse False: False
3.3.3.Logical operator: And
|
Module Tester
Sub Main()
Console.WriteLine("And" & vbCrLf & vbCrLf & _
"False And False: " & (False And False) & vbCrLf & _
"False And True: " & (False And True) & vbCrLf & _
"True And False: " & (True And False) & vbCrLf & _
"True And True: " & (True And True))
End Sub
End Module
|
3.3.4.Logical operator: Or
|
Module Tester
Sub Main()
Console.WriteLine("Or" & vbCrLf & _
vbCrLf & "False Or False: " & (False Or False) & _
vbCrLf & "False Or True: " & (False Or True) & _
vbCrLf & "True Or False: " & (True Or False) & _
vbCrLf & "True Or True: " & (True Or True))
End Sub
End Module
|
Module Tester
Sub Main()
Console.WriteLine("Xor" & vbCrLf & _
vbCrLf & "False Xor False: " & (False Xor False) & _
vbCrLf & "False Xor True: " & (False Xor True) & _
vbCrLf & "True Xor False: " & (True Xor False) & _
vbCrLf & "True Xor True: " & (True Xor True))
End Sub
End Module
|
3.3.6.Logical operator: Not
|
Module Tester
Sub Main()
Console.WriteLine("Not" & vbCrLf & vbCrLf & _
"Not False: " & (Not False) & vbCrLf & "Not True: " & _
(Not True))
End Sub
End Module
|
3.3.7.Use Logic operator Or to link two functions
|
Module LogicTest
Sub Main()
Dim x As Integer = 1
Dim y As Integer = 1
If A(x) Or B(y) Then
Console.WriteLine("x= " & CStr(x) & ", y = " & CStr(y))
End If
If A(x) OrElse B(y) Then
Console.WriteLine("x= " & CStr(x) & ", y = " & CStr(y))
End If
End Sub
Function A(ByVal v1 As Integer) As Boolean
Return True
End Function
Function B(ByVal v1 As Integer) As Boolean
Return True
End Function
End Module
|
3.3.8.Use logic operators in If statement: Not, And, Or
|
Module Module1
Sub Main()
Dim A As Boolean = False
Dim B As Boolean = True
Dim C As Boolean = True
If (Not A) Then
Console.WriteLine("Not A")
End If
If (B Or C) Then
Console.WriteLine("B Or C")
End If
If (B And C) Then
Console.WriteLine("B And C")
End If
End Sub
End Module
|
3.4.1.Use Mod to fix degree
|
Public Class Tester
Public Shared Function FixRange(ByVal origValue As Double, _
ByVal rangeMin As Double, ByVal rangeMax As Double) _
As Double
Dim shiftedValue As Double
Dim delta As Double
shiftedValue = origValue - rangeMin
delta = rangeMax - rangeMin
Return (((shiftedValue Mod delta) + delta) Mod delta) + _
rangeMin
End Function
Public Shared Sub Main
Dim result As New System.Text.StringBuilder
Dim formatDegrees As String = "Degrees: {0} Range: {1},{2} Value: {3}"
Dim formatRadians As String = "Radians: {0} Range: {1},{2} Value: {3}"
Dim degrees As Double
Dim radians As Double
Dim ranged As Double
' ----- Degrees over the range.
degrees = 367.75
ranged = FixRange(degrees, 0, 360)
result.AppendLine(String.Format(formatDegrees,degrees, 0, 360, ranged))
' ----- Radians over the range.
radians = Math.PI * 3.33
ranged = FixRange(radians, -Math.PI, Math.PI)
result.AppendLine(String.Format(formatRadians, _
radians, -Math.PI, Math.PI, ranged))
Console.WriteLine(result.ToString())
End Sub
End Class
|
|
Public Structure Diamond
Private weight As Single
Private price As Decimal
Private fWeight As Boolean
Public Sub New(oz As Single, pr As Decimal)
weight = oz
price = pr
fWeight = True
End Sub
Public Property ByWeight() As Boolean
Get
Return fWeight
End Get
Set
fWeight = Value
End Set
End Property
Public ReadOnly Property Size() As Single
Get
Return weight
End Get
End Property
Public Shared Operator > (operand1 As Diamond, operand2 As Diamond) As Boolean
If operand1.Price / operand1.Size > operand2.Price / operand2.Size Then
Return True
Else
Return False
End If
End Operator
Public Shared Operator < (operand1 As Diamond, operand2 As Diamond) As Boolean
If operand1.Price / operand1.Size < operand2.Price / operand2.Size Then
Return True
Else
Return False
End If
End Operator
Public Shared Operator Or (op1 As Diamond, op2 As Diamond) As Diamond
If op1.ByWeight And op2.ByWeight
If op1 < op2 Then
Return op1
Else
Return op2
End If
Else
If op1.ByWeight Then
Return op1
ElseIf op2.ByWeight Then
Return op2
Else
Return Nothing
End If
End If
End Operator
Public Shared Operator IsTrue(Byval op1 As Diamond) As Boolean
If op1.ByWeight Then
Return True
Else
Return False
End If
End Operator
Public Shared Operator IsFalse(ByVal op1 As Diamond) As Boolean
If op1.ByWeight Then
Return False
Else
Return True
End If
End Operator
End Structure
Public Module modTest
Public Sub Main()
Dim a As Diamond = New Diamond(1, .3d)
Dim b As Diamond = New Diamond(2, .5d)
a.ByWeight = False
b.ByWeight = True
If a Or b Then Console.WRiteLine(a.Size)
If a OrElse b Then Console.WriteLine(a.Size)
Console.WriteLine(b < a)
End Sub
End Module
|
3.6.1.Operator Precedence
|
Module Module1
Sub Main()
Dim Expression1 As Double
Dim Expression2 As Double
Dim Expression3 As Double
Dim Expression4 As Double
Expression1 = 5 ^ 2 + 1 * 3 - 4
Expression2 = 5 ^ (2 + 1) * 3 - 4
Expression3 = 5 ^ (2 + 1) * (3 - 4)
Expression4 = 5 ^ ((2 + 1) * (3 - 4))
Console.WriteLine(Expression1)
Console.WriteLine(Expression2)
Console.WriteLine(Expression3)
Console.WriteLine(Expression4)
End Sub
End Module
|
3.7.1.Using equality and relational operators.
|
Module Tester
Sub Main()
Dim number1, number2 As Integer
number1 = 10
number2 = 20
If number1 = number2 Then
Console.WriteLine("{0} = {1}", number1, number2)
End If
If number1 <> number2 Then
Console.WriteLine("{0} <> {1}", number1, number2)
End If
If number1 < number2 Then
Console.WriteLine("{0} < {1}", number1, number2)
End If
If number1 > number2 Then
Console.WriteLine("{0} > {1}", number1, number2)
End If
If number1 <= number2 Then
Console.WriteLine("{0} <= {1}", number1, number2)
End If
If number1 >= number2 Then
Console.WriteLine("{0} >= {1}", number1, number2)
End If
End Sub
End Module
|
3.8.1.String is Like 'regular expressions *'
|
public class Test
public Shared Sub Main
Dim s As String
s = "VB.Net"
If s Like "*VB.Net" Then Console.WriteLine("'VB.Net' is Like '*VB.Net'")
End Sub
End class
|
'VB.Net' is Like '?B.Net'
3.8.2.String is Like 'regular expressions ?' (question mark)
|
public class Test
public Shared Sub Main
Dim s As String
s = "VB.Net"
If s Like "?B.Net" Then Console.WriteLine("'VB.Net' is Like '?B.Net'")
End Sub
End class
|
'VB.Net' is Like '?B.Net'
3.9.1.Demonstrate 'is a' relationship
|
Class Tester
Shared Sub Main()
Dim point1, point2 As Point
Dim circle1, circle2 As Circle
point1 = New Point(30, 50)
circle1 = New Circle(120, 89, 2.7)
Console.WriteLine("Point point1: " & point1.ToString() & _
vbCrLf & "Circle circle1: " & circle1.ToString())
point2 = circle1
Console.WriteLine("Circle circle1 (via point2): " & point2.ToString())
circle2 = CType(point2, Circle) ' allowed only via cast
Console.WriteLine("Circle circle1 (via circle2): " & circle2.ToString())
If (TypeOf point1 Is Circle) Then
circle2 = CType(point1, Circle)
Console.WriteLine("cast successful")
Else
Console.WriteLine("point1 does not refer to a Circle")
End If
End Sub
End Class
Public Class Point
Private mX, mY As Integer
Public Sub New()
End Sub ' New
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer)
End Sub ' New
Public Overrides Function ToString() As String
Return "[" & mX & ", " & mY & "]"
End Function ' ToString
End Class
Public Class Circle
Inherits Point
Private mRadius As Double
Public Sub New()
End Sub ' New
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer, ByVal radiusValue As Double)
MyBase.New(xValue, yValue)
End Sub ' New
Public Overrides Function ToString() As String
Return "Center= " & MyBase.ToString() & _
"; Radius = " & mRadius
End Function ' ToString
End Class
|
Circle circle1: Center= [0, 0]; Radius = 0
Circle circle1 (via point2): Center= [0, 0]; Radius = 0
Circle circle1 (via circle2): Center= [0, 0]; Radius = 0
point1 does not refer to a Circle
3.9.2.Use Is and As to convert a class to its implenented Interface
|
Imports System
Interface Printable
Sub Read( )
Sub Write(ByVal obj As Object)
Property Status( ) As Integer
End Interface
Interface Zippable
Sub Zip( )
Sub Unzip( )
End Interface
Public Class Document
Implements Printable
Public Sub New(ByVal s As String)
Console.WriteLine("Creating document with: {0}", s)
End Sub
Public Sub Read( ) Implements Printable.Read
Console.WriteLine("Implementing the Read Method for Printable")
End Sub
Public Sub Write(ByVal o As Object) Implements Printable.Write
Console.WriteLine("Implementing the Write Method for Printable")
End Sub 'Write
Public Property Status( ) As Integer Implements Printable.Status
Get
Return Status
End Get
Set(ByVal Value As Integer)
Status = Value
End Set
End Property
Private myStatus As Integer = 0
End Class 'Document
Class Tester
Public Sub Run( )
End Sub 'Run
Shared Sub Main( )
Dim doc As New Document("Test Document")
If TypeOf doc Is Printable Then
Dim isDoc As Printable = doc
isDoc.Read( )
Else
Console.WriteLine("Could not cast to Printable")
End If
If TypeOf doc Is Zippable Then
Dim icDoc As Zippable = doc
icDoc.Zip( )
Else
Console.WriteLine("Could not cast to Zippable")
End If
End Sub 'Main
End Class
|
Creating document with: Test Document
Implementing the Read Method for Printable
Could not cast to Zippable
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