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Arrays and Procedures
 

Arrays and Procedures
 

Introduction

Because an array is primarily treated as a variable, it shares the regular characteristics of other objects. For example, an array can be passed as argument and a function can return an array. The main difference is that an array by itself represents a group of items while a regular variable considers only its own value.
 

Practical LearningPractical Learning: Introducing Arrays and Procedures
  1. Start Notepad
  2. In the empty file, type the following:
      
    Public Class IceCream
    Public Const BasePrice As Double = 1.55

    Public Sub ProcessAnOrder()
        Dim dFlv As Integer, dCont As Integer, dIngrd As Integer
        Dim Scoops As Integer
        Dim PriceIngredient As Double, TotalPrice As Double

        Dim Flavor() As String = {"Vanilla", "Cream of Cocoa", "Organic Strawberry", _
                   "Butter Pecan", "Cherry Coke", "Chocolate Brownies"}

        Dim Container(3) As String
        Container(0) = "Cone"
        Container(1) = "Cup"
        Container(2) = "Bowl"

        Dim Ingredient() As String = {"No Ingredient", "Peanuts", "M & M", "Cookies"}

        Console.WriteLine("Ice Cream Vendor Machine")

        Do
            Try
                Console.WriteLine("What type of flavor do you want?")
                Console.WriteLine("1 - {0}", Flavor(0))
                Console.WriteLine("2 - {0}", Flavor(1))
                Console.WriteLine("3 - {0}", Flavor(2))
                Console.WriteLine("4 - {0}", Flavor(3))
                Console.WriteLine("5 - {0}", Flavor(4))
                Console.WriteLine("6 - {0}", Flavor(5))
                Console.Write("Your Choice? ")
                dFlv = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If dFlv < 1 Or dFlv > 6 Then
                Console.WriteLine("Invalid Choice - Try Again!" & vbCrLf)
            End If
        Loop While dFlv < 1 Or dFlv > 6

        Do
            Try
                Console.WriteLine("What type of container do you want?")
                Console.WriteLine("1 - {0}", Container(0))
                Console.WriteLine("2 - {0}", Container(1))
                Console.WriteLine("3 - {0}", Container(2))
                Console.Write("Your Choice? ")
                dCont = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If dCont < 1 Or dCont > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While dCont < 1 Or dCont > 3

        Do
            Try
                Console.WriteLine("Do you want an ingredient or not")
                Console.WriteLine("1 - {0}", Ingredient(0))
                Console.WriteLine("2 - {0}", Ingredient(1))
                Console.WriteLine("3 - {0}", Ingredient(2))
                Console.WriteLine("4 - {0}", Ingredient(3))
                Console.Write("Your Choice? ")
                dIngrd = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If dIngrd < 1 Or dIngrd > 4 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While dIngrd < 1 Or dIngrd > 4

        Do
            Try
                Console.Write("How many scoops(1, 2, or 3)? ")
                Scoops = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If Scoops < 1 Or Scoops > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While Scoops < 1 Or Scoops > 3

        If dIngrd = 2 Or dIngrd = 3 Or dIngrd = 4 Then
            PriceIngredient = 0.65
        Else
            PriceIngredient = 0.0
        End If

        TotalPrice = (BasePrice * Scoops) + PriceIngredient

        DisplayReceipt(dFlv, dCont, dIngrd, Scoops, TotalPrice)
    End Sub

    Public Sub DisplayReceipt(ByVal Flv As Integer, ByVal Cont As Integer, _
                              ByVal Ingrd As Integer, _
                              ByVal spoons As Integer, ByVal TotalPrice As Double)
        Console.WriteLine(vbCrLf & "Ice Cream Order")

        Select Case Flv
            Case 2
                Console.WriteLine("Flavor:      Cream of Cocoa")
            Case 3
                Console.WriteLine("Flavor:      Organic Strawberry")
            Case 4
                Console.WriteLine("Flavor:      Butter Pecan")
            Case 5
                Console.WriteLine("Flavor:      Cherry Coke")
            Case 6
                Console.WriteLine("Flavor:      Chocolate Brownies")

            Case Else
                Console.WriteLine("Flavor:      Vavilla")
        End Select

        Select Case Cont
            Case 2
                Console.WriteLine("Container:   Cup")
            Case 3
                Console.WriteLine("Container:   Bowl")
            Case Else
                Console.WriteLine("Container:   Cone")
        End Select

        Select Case Ingrd
            Case 2
                Console.WriteLine("Ingredient:  Peanuts")
            Case 3
                Console.WriteLine("Ingredient:  M & M")
            Case 4
                Console.WriteLine("Ingredient:  Cookies")
            Case Else
                Console.WriteLine("Ingredient:  None")
        End Select

        Console.WriteLine("Scoops:      {0}", spoons)
        Console.WriteLine("Total Price: {0:C}" & vbCrLf, TotalPrice)
    End Sub
End Class
  3. Save the file in a new folder named IceCream2
  4. Save the file itself as IceCream.vb in the IceSream2 folder
  5. Start another instance of Notepad and type the following:
    Imports System

Public Class Exercise

    Public Shared Sub main()
        Dim ic As IceCream = New IceCream

        ic.ProcessAnOrder()
    End Sub
End Class
  6. Save the file as Exercise.vb in the IceCream2 folder
  7. Open the Command Prompt and switch to the IceCream2 folder
  8. Compile the exercise by typing vbc Exercise.vb and pressing Enter
  9. Execute the application by typing Exercise and pressing Enter. Here is an example of executing the program:
    Ice Cream Vendor Machine
What type of flavor do you want?
1 - Vanilla
2 - Cream of Cocoa
3 - Organic Strawberry
4 - Butter Pecan
5 - Cherry Coke
6 - Chocolate Brownies
Your Choice? 2
What type of container do you want?
1 - Cone
2 - Cup
3 - Bowl
Your Choice? 1
Do you want an ingredient or not
1 - No Ingredient
2 - Peanuts
3 - M & M
4 - Cookies
Your Choice? 3
How many scoops(1, 2, or 3)? 2

Ice Cream Order
Flavor:      Cream of Cocoa
Container:   Cone
Ingredient:  M & M
Scoops:      2
Total Price: $3.75
  10. Return to Notepad 
 

Passing a Member of an Array as Argument

Each member of an array is considered a sub-variable that is, a variable in its own right with a value. Based on this, you can pass a single member of an array as argument. In this case, you can pass the name of the array variable with the accompanying index to a procedure. Here is an example:

Imports System

Module Exercise
    Dim Names() As String = {"Hermine", "Gertrude", "Helene", "Paulette"}

    Private Sub ShowName(ByVal Name As String)
        Console.WriteLine("Name: {0}", Name)
    End Sub

    Public Sub main()
        ShowName(Names(2))

        Console.WriteLine()
    End Sub
End Module

This would produce:

Name: Helene

An Array Passed as Argument

The main purpose of using an array is to use various pseudo-variables grouped under one name. Still, an array is primarily a variable. As such, it can be passed to a procedure and it can be returned from one. Like a regular variable, an array can be passed as argument. To do this, in the parentheses of a procedure, provide the data type, the empty square brackets, and the name of the argument. Here is an example:

Imports System

Module Exercise
    Private Sub DisplayNumbers(ByVal args() As Double)

    End Sub

    Public Sub main()

    End Sub
End Module

When an array has been passed to a procedure, it can be used in the body of the procedure as any array can be, following the rules of array variables. For example, you can display its values. Because an array is derived from the Array class, an array passed as argument carries its number of members. This means that you don't have to pass an additional argument.

The simplest way you can use an array is to display the values of its members. This could be done as follows:

Imports System

Module Exercise
    Private Sub DisplayNumbers(ByVal args() As Double)
        For Each arg As Double In args
            Console.WriteLine("Number: {0}", arg)
        Next
    End Sub

    Public Sub main()

    End Sub
End Module

To call a procedure that takes an array as argument, simply type the name of the array in the parentheses of the called procedure. Here is an example:

Imports System

Module Exercise
    Private Sub DisplayNumbers(ByVal args() As Double)
        For Each arg As Double In args
            Console.WriteLine("Number: {0}", arg)
        Next
    End Sub

    Public Sub main()
        Dim number(4) As Double

        number(0) = 12.44
        number(1) = 525.38
        number(2) = 6.28
        number(3) = 2448.32
        number(4) = 632.04

        DisplayNumbers(number)
        Console.WriteLine()
    End Sub
End Module

This would produce:

Number: 12.44
Number: 525.38
Number: 6.28
Number: 2448.32
Number: 632.04

When an array is passed as argument to a procedure, the array is passed by reference. This means that, if the procedure makes any change to the array, the change would be kept when the procedure exits. This is illustrated in the following program:

Imports System

Module Exercise
    Private Sub DisplayNumber(ByVal args() As Double)
        For Each arg As Double In args
            Console.WriteLine("Number: {0}", arg)
        Next

        args(0) = -888.64
        args(1) = 24.57
        args(2) = 60450.24
        args(3) = -6.4
        args(4) = 900.002
    End Sub

    Public Sub main()
        Dim Numbers(4) As Double

        numbers(0) = 12.44
        numbers(1) = 525.38
        numbers(2) = 6.28
        Numbers(3) = 2448.32
        Numbers(4) = 632.04

        Console.WriteLine("=-= First Call =-=")
        For Each nbr As Double In Numbers
            Console.WriteLine("Number: {0}", nbr)
        Next
        Console.WriteLine()

        Console.WriteLine("=-= External Call =-=")
        DisplayNumber(Numbers)
        Console.WriteLine()

        Console.WriteLine("=-= Second Call =-=")
        For Each nbr As Double In Numbers
            Console.WriteLine("Number: {0}", nbr)
        Next
        Console.WriteLine()
    End Sub
End Module

This would produce:

=-= First Call =-=
Number: 12.44
Number: 525.38
Number: 6.28
Number: 2448.32
Number: 632.04

 =-= External Call =-=
Number: 12.44
Number: 525.38
Number: 6.28
Number: 2448.32
Number: 632.04

 =-= Second Call =-=
Number: -888.64
Number: 24.57
Number: 60450.24
Number: -6.4
Number: 900.002

In the Main function, the array is primarily initialized and its values are displayed to the screen. The array is then passed to an external procedure. That procedure receives the array ByVal. It displays the values of the array as they were passed it. Before exiting, the procedure modifies the array and closes. Back in Main(), the array is displayed without receiving any modification. But the values of the array appear different. This is because the array was modified by the called procedure. This illustrates that an array is passed by reference even if you don't use the ByRef keyword on the argument. You can use this characteristic to initialize an array from a procedure. Here is an example:

Imports System

Module Exercise
    Private Sub InitializeNumbers(ByVal args() As Double)
        args(0) = -888.64
        args(1) = 24.57
        args(2) = 60450.24
        args(3) = -6.4
        args(4) = 900.002
    End Sub

    Private Sub DisplayNumbers(ByVal nbrs() As Double)
        For Each nbr As Double In nbrs
            Console.WriteLine("Number: {0}", nbr)
        Next
    End Sub

    Public Sub main()
        Dim Numbers(4) As Double

        InitializeNumbers(Numbers)
        DisplayNumbers(Numbers)
        Console.WriteLine()
    End Sub
End Module

Notice that the InitializeList() procedure receives an un-initialized array but returns it with new values.

Because an array is passed by reference, if you want to explicitly indicate this, when passing an array, you can accompany it with the ByRef keyword. Here is an example:

Imports System

Module Exercise
    Private Sub InitializeNumbers(ByRef args() As Double)
        args(0) = 542.28
        args(1) = 64.96
        args(2) = 4750.25
        args(3) = 28.44
        args(4) = 18500.45
    End Sub

    Private Sub DisplayNumbers(ByVal nbrs() As Double)
        For Each nbr As Double In nbrs
            Console.WriteLine("Number: {0}", nbr)
        Next
    End Sub

    Public Sub main()
        Dim Numbers(4) As Double

        InitializeNumbers(Numbers)
        DisplayNumbers(Numbers)
        Console.WriteLine()
    End Sub
End Module

This would produce:

Number: 542.28
Number: 64.96
Number: 4750.25
Number: 28.44
Number: 18500.45
 

Practical LearningPractical Learning: Passing an Array as Argument
  1. To use examples of passing arrays to procedures, change the Order.vb file as follows:
      
    Public Class IceCream
    Public Const BasePrice As Double = 1.55

    Private Sub CreateFlavors(ByVal Flavors() As String)
        Flavors(0) = "Vanilla"
        Flavors(1) = "Cream of Cocoa"
        Flavors(2) = "Organic Strawberry"
        Flavors(3) = "Butter Pecan"
        Flavors(4) = "Cherry Coke"
        Flavors(5) = "Chocolate Brownies"
    End Sub

    Private Sub CreateIngredients(ByVal Ingredients() As String)
        Ingredients(0) = "No Ingredient"
        Ingredients(1) = "Peanuts"
        Ingredients(2) = "M & M"
        Ingredients(3) = "Cookies"
    End Sub

    Private Function ChooseContainer(ByVal Containers() As String) As Integer
        Dim choice As Integer = 1

        Do
            Try
                Console.WriteLine("What type of container do you want?")
                For i As Integer = 0 To 2
                    Console.WriteLine("{0} - {1}", i + 1, Containers(i))
                Next
                Console.Write("Your Choice? ")
                choice = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If choice < 1 Or choice > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While choice < 1 Or choice > 3

        Return choice
    End Function

    Private Function RequestFlavor(ByVal Flavors() As String) As Integer
        Dim choice As Integer = 1

        Do
            Try
                Console.WriteLine("What type of flavor do you want?")
                For i As Integer = 0 To 5
                    Console.WriteLine("{0} - {1}", i + 1, Flavors(i))
                Next
                Console.Write("Your Choice? ")
                choice = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If choice < 1 Or choice > 6 Then
                Console.WriteLine("Invalid Choice - Try Again!" & vbcrlf)
            End If
        Loop While choice < 1 Or choice > 6

        Return choice
    End Function

    Private Function RequestIngredient(ByVal Ingredients() As String) As Integer
        Dim choice As Integer = 1

        Do
            Try
                Console.WriteLine("Do you want an ingredient or not")
                For i As Integer = 0 To 3
                    Console.WriteLine("{0} - {1}", i + 1, Ingredients(i))
                Next
                Console.Write("Your Choice? ")
                choice = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If choice < 1 Or choice > 4 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While choice < 1 Or choice > 4

        Return choice
    End Function

    Private Function GetTheNumberOfScoops() As Integer
        Dim number As Integer = 1

        Do
            Try
                Console.Write("How many scoops(1, 2, or 3)? ")
                number = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If number < 1 Or number > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While number < 1 Or number > 3

        Return number
    End Function

    Public Sub ProcessAnOrder()
        Dim dFlv As Integer, dCont As Integer, dIngrd As Integer
        Dim Scoops As Integer
        Dim PriceIngredient As Double, PriceScoop As Double, TotalPrice As Double

        Dim Flavors(6) As String
        Dim Containers(3) As String
        Dim Ingredients(4) As String

        Containers(0) = "Cone"
        Containers(1) = "Cup"
        Containers(2) = "Bowl"

        CreateFlavors(Flavors)
        CreateIngredients(Ingredients)

        dFlv = RequestFlavor(Flavors)
        dCont = ChooseContainer(Containers)
        dIngrd = RequestIngredient(Ingredients)
        Scoops = GetTheNumberOfScoops()

        If dIngrd = 2 Or dIngrd = 3 Or dIngrd = 4 Then
            PriceIngredient = 0.5
        Else
            PriceIngredient = 0.0
        End If

        If Scoops = 1 Then
            PriceScoop = 0.65
        ElseIf Scoops = 2 Then
            PriceScoop = 1.05
        Else
            PriceScoop = 1.55
        End If

        Console.WriteLine("Ice Cream Vendor Machine")

        TotalPrice = BasePrice + PriceScoop + PriceIngredient

        DisplayReceipt(Flavors(dFlv - 1), Containers(dCont - 1), _
              Ingredients(dIngrd - 1), Scoops, TotalPrice)
    End Sub

    Public Sub DisplayReceipt(ByVal Flv As String, ByVal Cont As String, _
                              ByVal Ingrd As String, _
                              ByVal spoons As Integer, ByVal TotalPrice As Double)
        Console.WriteLine(vbCrLf & "Ice Cream Order")
        Console.WriteLine("Flavor:      {0}", Flv)
        Console.WriteLine("Container:   {0}", Cont)
        Console.WriteLine("Ingredient:  {0}", Ingrd)
        Console.WriteLine("Scoops:      {0}", spoons)
        Console.WriteLine("Total Price: {0:C}" & vbCrLf, TotalPrice)
    End Sub

End Class
  2. Save, compile, and test the program. Here is an example of running the program:
      
    What type of flavor do you want?
1 - Vanilla
2 - Cream of Cocoa
3 - Organic Strawberry
4 - Butter Pecan
5 - Cherry Coke
6 - Chocolate Brownies
Your Choice? 0
Invalid Choice - Try Again!

What type of flavor do you want?
1 - Vanilla
2 - Cream of Cocoa
3 - Organic Strawberry
4 - Butter Pecan
5 - Cherry Coke
6 - Chocolate Brownies
Your Choice? 7
Invalid Choice - Try Again!

What type of flavor do you want?
1 - Vanilla
2 - Cream of Cocoa
3 - Organic Strawberry
4 - Butter Pecan
5 - Cherry Coke
6 - Chocolate Brownies
Your Choice? 5
What type of container do you want?
1 - Cone
2 - Cup
3 - Bowl
Your Choice? 0
Invalid Choice - Try Again!
What type of container do you want?
1 - Cone
2 - Cup
3 - Bowl
Your Choice? 3
Do you want an ingredient or not
1 - No Ingredient
2 - Peanuts
3 - M & M
4 - Cookies
Your Choice? 0
Invalid Choice - Try Again!
Do you want an ingredient or not
1 - No Ingredient
2 - Peanuts
3 - M & M
4 - Cookies
Your Choice? 8
Invalid Choice - Try Again!
Do you want an ingredient or not
1 - No Ingredient
2 - Peanuts
3 - M & M
4 - Cookies
Your Choice? 4
How many scoops(1, 2, or 3)? 2
Ice Cream Vendor Machine

Ice Cream Order
Flavor: Cherry Coke
Container: Bowl
Ingredient: Cookies
Scoops: 2
Total Price: $3.10
  3. Return to Notepad

A Function that Returns an Array

In the previous section, we saw that a (sub) procedure could return an array because if it modifies an array it receives as argument, the array keeps the new value. Still, you can use a function to formally return an array. When declaring or defining the function, you must specify its data type.

To create a function that returns an array, on the left of the function's name, provide the type of value that the returned array  will be made of, followed by empty parentheses. Here is an example:

Private Function InitializeValues() As Double()
        
End Function

Remember that a function must always return an appropriate value depending on how it was declared. In this case, if it was specified as returning an array, then make sure it returns an array and not a regular variable. One way you can do this is to declare and possibly initialize a local array variable. After using the local array, you return only its name (without the parentheses). Here is an example:

Private Function InitializeValues() As Double()
        Dim Values(4) As Double

        Values(0) = 542.28
        Values(1) = 64.96
        Values(2) = 4750.25
        Values(3) = 28.44
        Values(4) = 18500.45
        InitializeValues = Values
End Function

When a function returns an array, that function can be assigned to an array declared locally when you want to use it. Remember to initialize a variable with such a function only if the variable is an array. If you initialize an array variable with a procedure that doesn't return an array, you would receive an error.

Here is an example:

 
Imports System

Module Exercise
    Private Function InitializeValues() As Double()
        Dim Values(4) As Double

        Values(0) = 542.28
        Values(1) = 64.96
        Values(2) = 4750.25
        Values(3) = 28.44
        Values(4) = 18500.45
        InitializeValues = Values
    End Function

    Private Sub DisplayNumbers(ByVal nbrs() As Double)
        For Each nbr As Double In nbrs
            Console.WriteLine("Number: {0}", nbr)
        Next
    End Sub

    Public Sub main()
        Dim Numbers(4) As Double

        Numbers = InitializeValues()
        DisplayNumbers(Numbers)
        Console.WriteLine()
    End Sub
End Module

This would produce:

Number: 542.28
Number: 64.96
Number: 4750.25
Number: 28.44
Number: 18500.45

Practical LearningPractical Learning: Returning an Array From a Procedure
  1. To apply an example of returning an array from a function, and to complete this exercise change the Order.vb file as follows:
      
    Public Class IceCream
    Public Const BasePrice As Double = 1.55

    Dim ChoiceFlavor As Integer
    Dim ChoiceContainer As Integer
    Dim ChoiceIngredient As Integer
    Dim Scoops As Integer
    Dim TotalPrice As Double

    Private Function PrepareFlavors() As String()
        Dim Flavors(10) As String

        Flavors(0) = "Vanilla"
        Flavors(1) = "Cream of Cocoa"
        Flavors(2) = "Chocolate Chip"
        Flavors(3) = "Organic Strawberry"
        Flavors(4) = "Butter Pecan"
        Flavors(5) = "Cherry Coke"
        Flavors(6) = "Chocolate Brownies"
        Flavors(7) = "Caramel Au Lait"
        Flavors(8) = "Chunky Butter"
        Flavors(9) = "Chocolate Cookie"

        Return Flavors
    End Function

    Private Sub CreateIngredients(ByRef Ingredients() As String)
        Ingredients(0) = "No Ingredient"
        Ingredients(1) = "Peanuts"
        Ingredients(2) = "M & M"
        Ingredients(3) = "Cookies"
    End Sub

    Private Sub ChooseContainer(ByRef Containers() As String)
        Containers(0) = "Cone"
        Containers(1) = "Cup"
        Containers(2) = "Bowl"

        Do
            Try
                Console.WriteLine("What type of container do you want?")
                For i As Integer = 0 To 2 Step 1
                    Console.WriteLine("{0} - {1}", i + 1, Containers(i))
                Next
                Console.Write("Your Choice? ")
                ChoiceContainer = CInt(Console.ReadLine())

            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If ChoiceContainer < 1 Or ChoiceContainer > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While ChoiceContainer < 1 Or ChoiceContainer > 3
    End Sub

    Private Sub RequestFlavor(ByRef Flavors() As String)
        Flavors = PrepareFlavors()

        Do
            Try
                Console.WriteLine("What type of flavor do you want?")
                For i As Integer = 0 To 9 Step 1
                    Console.WriteLine("{0} - {1}", i + 1, Flavors(i))
                Next
                Console.Write("Your Choice? ")
                ChoiceFlavor = CInt(Console.ReadLine())

            Catch exc As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If ChoiceFlavor < 1 Or ChoiceFlavor > 10 Then
                Console.WriteLine("Invalid Choice - Try Again!" & vbCrLf)
            End If
        Loop While ChoiceFlavor < 1 Or ChoiceFlavor > 10
    End Sub

    Private Sub ProcessIngredients(ByRef Ingredients() As String)
        CreateIngredients(Ingredients)

        Do
            Try
                Console.WriteLine("Do you want an ingredient or not")
                For i As Integer = 0 To 3 Step 1
                    Console.WriteLine("{0} - {1}", i + 1, Ingredients(i))
                Next
                Console.Write("Your Choice? ")
                ChoiceIngredient = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If ChoiceIngredient < 1 Or ChoiceIngredient > 4 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While ChoiceIngredient < 1 Or ChoiceIngredient > 4
    End Sub

    Private Sub GetTheNumberOfScoops()
        Do
            Try
                Console.Write("How many scoops(1, 2, or 3)? ")
                Scoops = CInt(Console.ReadLine())
            Catch ex As InvalidCastException
                Console.WriteLine("You must enter a valid number and no other character!")
            End Try

            If Scoops < 1 Or Scoops > 3 Then
                Console.WriteLine("Invalid Choice - Try Again!")
            End If
        Loop While Scoops < 1 Or Scoops > 3
    End Sub

    Public Sub ProcessAnOrder()
        Dim PriceIngredient As Double, PriceScoop As Double

        Dim Flavor(10) As String
        Dim Container(3) As String
        Dim Ingredient(4) As String

        RequestFlavor(Flavor)
        ChooseContainer(Container)
        ProcessIngredients(Ingredient)
        GetTheNumberOfScoops()

        If ChoiceIngredient = 2 Or ChoiceIngredient = 3 Or ChoiceIngredient = 4 Then
            PriceIngredient = 0.5
        Else
            PriceIngredient = 0.0
        End If

        If Scoops = 1 Then
            PriceScoop = 0.65
        ElseIf Scoops = 2 Then
            PriceScoop = 1.05
        Else
            PriceScoop = 1.55
        End If

        Console.WriteLine("Ice Cream Vendor Machine")

        TotalPrice = BasePrice + PriceScoop + PriceIngredient

        DisplayReceipt(Flavor, Container, Ingredient)
    End Sub

    Public Sub DisplayReceipt(ByRef Flv() As String, ByRef Cont() As String, _
                              ByRef Ingrd() As String)

        Console.WriteLine(vbCrLf & "Ice Cream Order")
        Console.WriteLine("Flavor:      {0}", Flv(ChoiceFlavor))
        Console.WriteLine("Container:   {0}", Cont(ChoiceContainer))
        Console.WriteLine("Ingredient:  {0}", Ingrd(ChoiceIngredient))
        Console.WriteLine("Scoops:      {0}", Scoops)
        Console.WriteLine("Total Price: {0:C}" & vbCrLf, TotalPrice)
    End Sub

End Class
  2. Save, compile, and test the program. Then return to Notepad
 
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