i\'m working on a visual basic problem for homework. I\'m supposed to be making

Question

i'm working on a visual basic problem for homework. I'm supposed to be making a form to display the total cost of a restaurant bill. It's asking for a sub procedure for the quantity of item inputs, then a function to calculate total cost, and another sub procedure to display everything.
This is what i have so far:


Public Class Form1


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fmtstr As String = "{0,-10}{1,20}{2,50}"
Dim pizza, fries, drinks, p1, p2, p3, total As Double
p1 = 1.75
p2 = 2.0
p3 = 1.25
input(pizza, fries, drinks)
disp(fmtstr, pizza, fries, drinks, p1, p2, p3, total)
Calc(pizza, fries, drinks, total)

End Sub
Sub input(ByRef pizza As Double, ByRef fries As Double, ByRef drinks As Double)
pizza = TextBox1.Text
fries = TextBox2.Text
drinks = TextBox3.Text
End Sub

Sub disp(ByVal fmtstr As String, ByVal pizza As Double, ByVal fries As Double, ByVal drinks As Double, ByVal p1 As Double, ByVal p2 As Double, ByVal p3 As Double, ByVal total As Double)
ListBox1.Items.Clear()
ListBox1.Items.Add(String.Format(fmtstr, "Item", "Quantity", "Price"))
ListBox1.Items.Add("")
ListBox1.Items.Add(String.Format(fmtstr, "Pizza Slices", pizza, (FormatCurrency(p1))))
ListBox1.Items.Add(String.Format(fmtstr, "Fries", fries, (FormatCurrency(p2))))
ListBox1.Items.Add(String.Format(fmtstr, "Soft Drinks", drinks, (FormatCurrency(p3))))
fmtstr = "{0,-10}{1,70}
ListBox1.Items.Add(String.Format(fmtstr, "Total", (FormatCurrency(total))))
End Sub


Function Calc(ByRef pizza As Double, ByRef fries As Double, ByRef drinks As Double, ByVal total As Double) As Double

total = pizza + fries + drinks
Return total

End Function

End Class

The only problem i'm having is that the total comes up as $0.00
What am i doing wrong? textbox1,2,3 are the input boxes where the number of items is put.
im guessing that the problem is that im programming it wrong where the values of the items input aren't reading. p1,2,3 are the prices for the items.
Any help would be greatly appreciated.

Explanation / Answer

Hi,

1) Modify your code for button click

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fmtstr As String = "{0,-10}{1,20}{2,50}"
Dim pizza, fries, drinks, p1, p2, p3, total As Double
p1 = 1.75
p2 = 2.0
p3 = 1.25
input(pizza, fries, drinks)
total = Calc(pizza, fries, drinks, p1, p2, p3, total)
disp(fmtstr, pizza, fries, drinks, p1, p2, p3, total)
End Sub

2) And Function Calc is not calculating the prices because pizza, fries, drinks are the item Quantities. You can modify Calc function as below

Function Calc(ByRef pizza As Double, ByRef fries As Double, ByRef drinks As Double, ByRef p1 As Double, ByRef p2 As Double, ByRef p3 As Double, ByVal total As Double) As Double

total = (pizza * p1) + (fries * p2) + (drinks * p3)
Return total

End Function

I hope it helps :)

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