on creating a class

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  14 years ago

  by D Ashcroft

  dan ashcroft

  Cirencester / San Juan, Puerto Rico

  Joined 15 years ago
  Hello  In my Deitel book  there is this exercise. (p442)
  
  

  (This is an application that allows user to enter the lengths of the 3 sides of a triangle)

   "Define a constructor that will take the three lengths of the three sides of the triangle as arguments. Create 3 properties that enable clients to access and modify the lengths of the three sides.If the user enters a negative value that side should be assigned a 0 value"

   

  I have gotten  this far:

  Public Class Triangle

  'declare integers for each of the 3 sides

  Private m_intSideOne As Integer

  Private m_intSideTwo As Integer

  Private m_intSideThree As Integer

  'Triangle constructor, sides supplied

  Public Sub New(ByVal SideOne As Integer, ByVal SideTwo As Integer, ByVal SideThree As Integer)

  SideA = SideOne

  SideB = SideTwo

  SideC = SideThree

  End Sub

  'property SideA

  Public Property SideA() As Integer

  Get

  Return m_intSideOne

  End Get

  Set(ByVal Value As Integer)

  'if the value entered is a negative

  If (Value > 0) Then

  m_intSideOne = Value

  Else

  m_intSideOne = 0

  End If

  End Set

  End Property

  Public Property SideB() As Integer

  Get

  Return m_intSideTwo

  End Get

  Set(ByVal Value As Integer)

  If (Value > 0) Then

  m_intSideTwo = Value

  Else

  m_intSideTwo = 0

  End If

  End Set

  End Property

  Public Property SideC() As Integer

  Get

  Return m_intSideThree

  End Get

  Set(ByVal Value As Integer)

  If (Value > 0) Then

  m_intSideThree = Value

  Else

  m_intSideThree = 0

  End If

  End Set

  End Property

  End Class

  but then there is this :

  "Create two more properties in the Triangle class. One determines wheather the sides form a right angle. The other an equilateral triangle. These properties are considered read only because you only define a Get accessor....."

  this last requirement is giving me the problem. I would have just written it as an If... statement in the application not in the Class.

  any advice much appreciated as always.

  DA
  
  

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  14 years ago

  by Nimpo

  Mitch ★

  Denver, United States

  Joined 16 years ago

  You could do something like:
  

  Public ReadOnly Property IsEquilateral() As Boolean
     Get
        Return (Me.SideA = Me.SideB) AndAlso (Me.SideB = Me.SideC)
     End Get
  End Propery
  
  Public ReadOnly Property IsRightTriangle() As Boolean
     Get
        'If C is not always the hypotenus,
        'You will need to find the longest side
        'And treat that as SideC
        Return Me.SideA ^ 2 + Me.SideB ^ 2 = Me.SideC ^ 2
     End Get
  End Property
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  The reason for doing this in the class is to provide a common function so the user doesn't have to do it himself.  But this is more as an example anyway and not a "real-world" class...
  
  
  
  
  

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  14 years ago

  by D Ashcroft

  dan ashcroft

  Cirencester / San Juan, Puerto Rico

  Joined 15 years ago

  dear Nimpo :
  thanks for the feedback, it really helped me on my way. This is what I cooked up after a long lean look: maybe you can see any way that i might have done it better ? i think the calculations for what makes a Right Triangle are way off, but like you said, its more of an example and has shown me how to create a class and how to make an object of it.
  
  Public Class Triangle
     'declare integers for each of the 3 sides
     Private mintSideOne As Integer
     Private mintSideTwo As Integer
     Private mintSideThree As Integer
  
     'Triangle constructor, sides supplied
     Public Sub New(ByVal SideOne As Integer, ByVal SideTwo As Integer, ByVal SideThree As Integer)
  
        SideA = SideOne
        SideB = SideTwo
        SideC = SideThree
     End Sub
  
     'property SideA
     Public Property SideA() As Integer
        Get
           Return mintSideOne
        End Get
        Set(ByVal Value As Integer)
           'if the value entered is a negative
           If (Value > 0) Then
              mintSideOne = Value
           Else
              mintSideOne = 0
           End If
  
        End Set
     End Property
  
     Public Property SideB() As Integer
        Get
           Return mintSideTwo
        End Get
        Set(ByVal Value As Integer)
           If (Value > 0) Then
              mintSideTwo = Value
           Else
              mintSideTwo = 0
           End If
  
        End Set
     End Property
  
     Public Property SideC() As Integer
        Get
           Return mintSideThree
        End Get
  
        Set(ByVal Value As Integer)
           If (Value > 0) Then
              mintSideThree = Value
           Else
              mintSideThree = 0
           End If
        End Set
     End Property
  
     Public ReadOnly Property IsEquilateral() As Boolean
        Get
           Return (Me.SideA = Me.SideB) And (Me.SideB = Me.SideC) AndAlso (Me.SideA = Me.SideC)
        End Get
     End Property
  
     Public ReadOnly Property IsRightTriangle() As Boolean
        Get
           'If C is not always the hypotenus,
           'You will need to find the longest side
           'And treat that as SideC
           Return (Me.SideA = Me.SideB)Or (Me.SideA = Me.SideB)Or (Me.SideB=Me.SideA) Or (Me.SideB=Me.SideC) _
           Or (Me.SideC=Me.SideA) Or (Me.SideC = Me.SideB)
        End Get
     End Property
  
  
  End Class
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

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  14 years ago

  by Nimpo

  Mitch ★

  Denver, United States

  Joined 16 years ago

  The calculations I gave should be correct.  An equilateral triangle is one in which all 3 sides have equal lengths (so if A = B and B = C then you don't even have to check if A = C.  AndAlso is slightly faster than And in some cases because if the first condition is False, it doesn't bother evaluating the second, since it's irrelevant).
  
  A rigth triangle is one in which one angle = 90 degrees (pi/2 radians).  Every right triangle has the property so that A^2 + B^2 = C^2 (C must be the side opposite the right angle/the longest side/the hypotenuse, they are all the same things).  Thus, if this statement isn't True, you do not have a right triangle.
  
  
  
  
  
  

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