Function procedures

[Michelle Monty]

I'm creating an application where a user creates a cable bill. The application calculates the bill based on whether the customer is a residential or business customer. I've finished the interface and all of the calculations. However, the assignment is to use one or more sub or function procedures. I have several sub procedures but I don't have any function procedures and I'm not sure how to include one in my program without messing up what I've created. Any advice would be greatly appreciated. Thanks! Here's my code:

'Project Name: Tammy Seilheimer
'Project Purpose: This project calculates a customer's bill for cable services
'Created By: Tammy Seilheimer

Option Explicit On
 
Public Class Form1
 
    Private Sub residentialButton_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles residentialbutton.CheckedChanged
        connectionstextbox.Visible = False
        connectionsquantitytextbox.Visible = False
        TextBox4.Visible = False
        Label7.Visible = False
        Label8.Visible = False
 
    End Sub
 
    Private Sub businessbutton_checkedchanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles businessbutton.CheckedChanged
        connectionstextbox.Visible = True
        connectionsquantitytextbox.Visible = True
        TextBox4.Visible = True
        Label7.Visible = True
        Label8.Visible = True
    End Sub
 
 
    Private Sub calculatebutton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calculatebutton.Click
 
        If residentialbutton.Checked Then
            Dim channelprice As Decimal
            Dim residentialnumberofchannels As Integer
            Dim residentialchanneltotalprice As Decimal
            Dim residentialamountdue As Decimal
            Dim processingfee As Decimal
            Dim basicfee As Decimal
            Dim isconverted As Boolean
            Dim isconverted2 As Boolean
            Dim isconverted3 As Boolean
            Dim isconverted4 As Boolean
            isconverted = Integer.TryParse(channelpricetextbox.Text, channelprice)
            isconverted2 = Integer.TryParse(processingtextbox.Text, processingfee)
            isconverted3 = Integer.TryParse(basicfeetextbox.Text, basicfee)
            isconverted4 = Integer.TryParse(premiumquantitytextbox.Text, residentialnumberofchannels)
            'connectionstextbox.Visible = False
            'connectionsquantitytextbox.Visible = False
            ' TextBox4.Visible = False
            'Label7.Visible = False
            'Label8.Visible = False
 
 
            If isconverted4 = True Then
                processingfee = 4.5
                basicfee = 30
                channelprice = 5
                premiumquantitytextbox.Text = residentialnumberofchannels
                channelpricetextbox.Text = channelprice.ToString("C2")
                residentialchanneltotalprice = (residentialnumberofchannels * channelprice)
                channeltextbox.Text = residentialchanneltotalprice.ToString("C2")
                processingtextbox.Text = processingfee.ToString("C2")
                basicfeetextbox.Text = basicfee.ToString("C2")
                residentialamountdue = (processingfee + basicfee + residentialchanneltotalprice)
                amountduetextbox.Text = residentialamountdue.ToString("C2")
 
            End If
        End If
 
        If businessbutton.Checked Then
 
            Dim businessnumberofchannels As Integer
            Dim businessnumberofconnections As Integer
            Dim businesschanneltotalprice As Decimal
            Dim businessconnectionstotalprice As Decimal
            Dim businessamountdue As Decimal
            Dim channelprice As Decimal
            Dim isconverted5 As Boolean
            Dim isconverted6 As Boolean
            Dim processingfee As Decimal
            Dim basicfee As Decimal
            Dim connectionprice As Decimal
            isconverted5 = Integer.TryParse(connectionsquantitytextbox.Text, businessnumberofconnections)
            isconverted6 = Integer.TryParse(premiumquantitytextbox.Text, businessnumberofchannels)
 
            If isconverted5 = True Then
                processingfee = 16.5
                basicfee = 80
                channelprice = 50
                connectionprice = 4
                businessconnectionstotalprice = businessnumberofconnections * 4
                businessnumberofconnections = connectionsquantitytextbox.Text
                channelpricetextbox.Text = channelprice.ToString("C2")
                connectionstextbox.Text = businessconnectionstotalprice.ToString("C2")
                TextBox4.Text = connectionprice.ToString("C2")
                processingtextbox.Text = processingfee.ToString("C2")
                basicfeetextbox.Text = basicfee.ToString("C2")
                businesschanneltotalprice = businessnumberofchannels * 50
                channeltextbox.Text = businesschanneltotalprice.ToString("C2")
                businessnumberofchannels = premiumquantitytextbox.Text
                businessamountdue = (businesschanneltotalprice + processingfee + basicfee + businessconnectionstotalprice)
                amountduetextbox.Text = businessamountdue.ToString("C2")
 
            End If
        End If
 
 
    End Sub
 
 
    Private Sub exitbutton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Exitbutton.Click
        Me.Close()
    End Sub
 
    Private Sub clearbutton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles clearbutton.Click
        processingtextbox.Text = String.Empty
        basicfeetextbox.Text = String.Empty
        connectionsquantitytextbox.Text = String.Empty
        connectionstextbox.Text = String.Empty
        premiumquantitytextbox.Text = String.Empty
        channelpricetextbox.Text = String.Empty
        channeltextbox.Text = String.Empty
        amountduetextbox.Text = String.Empty
        TextBox4.Text = String.Empty
    End Sub
 
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
    End Sub
End Class

[debasisdas]

Functions are created mainly to return a value. If you want only a sub routine and have nothing to return then procedure is better.

[balabaster]

Functions are created mainly to return a value. If you want only a sub routine and have nothing to return then procedure is better.

Something that always astounds me with computer courses (at least in my experience) is that they never really teach code reuse and efficiency of code structure...it's like they put a bunch of concepts out there and tell the students to get on with it. My university course was the exact same way all those years ago - and I've had a lot of on the job learning to do since then.

Obviously you're aware that a sub(routine) (which equates to a procedure) is just a code block that doesn't need to return any values. A function is similar except it returns values.

 
Sub MyDemoSub(ByVal Param1 As String, ByVal Param2 As String)
'Do something that requires knowing Param1 and Param2 to
'achieve the objective. 
End Sub
 
Function MyDemoFunction(ByVal Param1 As String, ByVal Param2 As String) As Boolean
'Do something that requires knowing Param1 and Param2 to
'achieve the objective and return some value.
Return Param1 = Param2
End Function
 

As you can see, the demo function just compares the values passed into parameter 1 and parameter 2 and if they are the same, the function returns the value true. Obviously your subs and functions can have as few or as many parameters as you need - but the purpose of them is to allow code re-use...the ability to run through a procedure with a single line of code.

Dim MyValue1 As String = "Hello" 
Dim MyValue2 As String = "World"
'We want to see if the values in MyValue1 and MyValue2 are the same
Dim MyBoolean As Boolean = MyDemoFunction(MyValue1, MyValue2)
'At this point MyBoolean = False
 

Now for the purpose of this demo, the code example is actually longer than the code it would've taken to do:
Dim MyBool As Boolean = (MyValue1 = MyValue2)
But you can easily see that any procedure as complex as needed could be contained within the bounds of the function and any data types could be passed as parameters and any data types could be returned.

It would be fairly simple to include a few functions - I'll start you off with one very basic one - you would probably want something a little more complex to make your code more usable but this will give you an idea of what you're looking for:

Function ResidentialTotal(ByVal NumberOfChannels As Integer, ByVal ChannelPrice As Decimal) As Decimal
  Return NumberOfChannels * ChannelPrice 
End Function
 

You would call this from your main procedure in the following manner:

residentialchanneltotalprice = ResidentialTotal(residentialnumberofchannels, channelprice)
 

I started you off with such a simple one because as this is an assignment you should really be learning the benefit of this type of code structure so you should really get to grips with using it. Using that example directly in your code probably won't earn you the best marks because it uses more code than your original - it just demonstrates the concept.

[Michelle Monty]

Thanks, that helped a lot.

Something that always astounds me with computer courses (at least in my experience) is that they never really teach code reuse and efficiency of code structure...it's like they put a bunch of concepts out there and tell the students to get on with it. My university course was the exact same way all those years ago - and I've had a lot of on the job learning to do since then.

Obviously you're aware that a sub(routine) (which equates to a procedure) is just a code block that doesn't need to return any values. A function is similar except it returns values.

 
Sub MyDemoSub(ByVal Param1 As String, ByVal Param2 As String)
'Do something that requires knowing Param1 and Param2 to
'achieve the objective. 
End Sub
 
Function MyDemoFunction(ByVal Param1 As String, ByVal Param2 As String) As Boolean
'Do something that requires knowing Param1 and Param2 to
'achieve the objective and return some value.
Return Param1 = Param2
End Function
 

As you can see, the demo function just compares the values passed into parameter 1 and parameter 2 and if they are the same, the function returns the value true. Obviously your subs and functions can have as few or as many parameters as you need - but the purpose of them is to allow code re-use...the ability to run through a procedure with a single line of code.

Dim MyValue1 As String = "Hello" 
Dim MyValue2 As String = "World"
'We want to see if the values in MyValue1 and MyValue2 are the same
Dim MyBoolean As Boolean = MyDemoFunction(MyValue1, MyValue2)
'At this point MyBoolean = False
 

Now for the purpose of this demo, the code example is actually longer than the code it would've taken to do:
Dim MyBool As Boolean = (MyValue1 = MyValue2)
But you can easily see that any procedure as complex as needed could be contained within the bounds of the function and any data types could be passed as parameters and any data types could be returned.

It would be fairly simple to include a few functions - I'll start you off with one very basic one - you would probably want something a little more complex to make your code more usable but this will give you an idea of what you're looking for:

Function ResidentialTotal(ByVal NumberOfChannels As Integer, ByVal ChannelPrice As Decimal) As Decimal
  Return NumberOfChannels * ChannelPrice 
End Function
 

You would call this from your main procedure in the following manner:

residentialchanneltotalprice = ResidentialTotal(residentialnumberofchannels, channelprice)
 

I started you off with such a simple one because as this is an assignment you should really be learning the benefit of this type of code structure so you should really get to grips with using it. Using that example directly in your code probably won't earn you the best marks because it uses more code than your original - it just demonstrates the concept.