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

[code=vbnet]
Option Explicit On

Public Class Form1

Private Sub residentialButt on_CheckedChang ed(ByVal sender As Object, ByVal e As System.EventArg s) Handles residentialbutt on.CheckedChang ed
connectionstext box.Visible = False
connectionsquan titytextbox.Vis ible = False
TextBox4.Visibl e = False
Label7.Visible = False
Label8.Visible = False

End Sub

Private Sub businessbutton_ checkedchanged( ByVal sender As Object, ByVal e As System.EventArg s) Handles businessbutton. CheckedChanged
connectionstext box.Visible = True
connectionsquan titytextbox.Vis ible = True
TextBox4.Visibl e = True
Label7.Visible = True
Label8.Visible = True
End Sub


Private Sub calculatebutton _Click(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles calculatebutton .Click

If residentialbutt on.Checked Then
Dim channelprice As Decimal
Dim residentialnumb erofchannels As Integer
Dim residentialchan neltotalprice As Decimal
Dim residentialamou ntdue 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.TryPars e(channelpricet extbox.Text, channelprice)
isconverted2 = Integer.TryPars e(processingtex tbox.Text, processingfee)
isconverted3 = Integer.TryPars e(basicfeetextb ox.Text, basicfee)
isconverted4 = Integer.TryPars e(premiumquanti tytextbox.Text, residentialnumb erofchannels)
'connectionstex tbox.Visible = False
'connectionsqua ntitytextbox.Vi sible = False
' TextBox4.Visibl e = False
'Label7.Visible = False
'Label8.Visible = False


If isconverted4 = True Then
processingfee = 4.5
basicfee = 30
channelprice = 5
premiumquantity textbox.Text = residentialnumb erofchannels
channelpricetex tbox.Text = channelprice.To String("C2")
residentialchan neltotalprice = (residentialnum berofchannels * channelprice)
channeltextbox. Text = residentialchan neltotalprice.T oString("C2")
processingtextb ox.Text = processingfee.T oString("C2")
basicfeetextbox .Text = basicfee.ToStri ng("C2")
residentialamou ntdue = (processingfee + basicfee + residentialchan neltotalprice)
amountduetextbo x.Text = residentialamou ntdue.ToString( "C2")

End If
End If

If businessbutton. Checked Then

Dim businessnumbero fchannels As Integer
Dim businessnumbero fconnections As Integer
Dim businesschannel totalprice As Decimal
Dim businessconnect ionstotalprice As Decimal
Dim businessamountd ue 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.TryPars e(connectionsqu antitytextbox.T ext, businessnumbero fconnections)
isconverted6 = Integer.TryPars e(premiumquanti tytextbox.Text, businessnumbero fchannels)

If isconverted5 = True Then
processingfee = 16.5
basicfee = 80
channelprice = 50
connectionprice = 4
businessconnect ionstotalprice = businessnumbero fconnections * 4
businessnumbero fconnections = connectionsquan titytextbox.Tex t
channelpricetex tbox.Text = channelprice.To String("C2")
connectionstext box.Text = businessconnect ionstotalprice. ToString("C2")
TextBox4.Text = connectionprice .ToString("C2")
processingtextb ox.Text = processingfee.T oString("C2")
basicfeetextbox .Text = basicfee.ToStri ng("C2")
businesschannel totalprice = businessnumbero fchannels * 50
channeltextbox. Text = businesschannel totalprice.ToSt ring("C2")
businessnumbero fchannels = premiumquantity textbox.Text
businessamountd ue = (businesschanne ltotalprice + processingfee + basicfee + businessconnect ionstotalprice)
amountduetextbo x.Text = businessamountd ue.ToString("C2 ")

End If
End If


End Sub


Private Sub exitbutton_Clic k(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles Exitbutton.Clic k
Me.Close()
End Sub

Private Sub clearbutton_Cli ck(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles clearbutton.Cli ck
processingtextb ox.Text = String.Empty
basicfeetextbox .Text = String.Empty
connectionsquan titytextbox.Tex t = String.Empty
connectionstext box.Text = String.Empty
premiumquantity textbox.Text = String.Empty
channelpricetex tbox.Text = String.Empty
channeltextbox. Text = String.Empty
amountduetextbo x.Text = String.Empty
TextBox4.Text = String.Empty
End Sub


Private Sub Form1_Load(ByVa l sender As System.Object, ByVal e As System.EventArg s) Handles MyBase.Load

End Sub
End Class[/code]

[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.