Drink Vending Machine Code - vb.net

Question

Hello Stackflow community,
I'm currently taking a class in Visual Basic and I'm in need of some assistance. I am creating a program that simulates a Drink Vending Machine using an array. The instructions follow:
Create an application that simulates a soft-drink vending machine. The application should let the user select one of the following soft drinks:
Cola ($1.00 each)
Root Beer ($1.00 each)
Lemon Lime Soda ($1.00 each)
Grape Soda ($1.50 each)
Cream Soda ($1.50 each)
When the application starts, the vending machine will have 20 of each type of soft drink. Each time the user selects a drink, the application should subtract 1 from the quantity of the selected drink. It should also update and display the total amount of sales. If the user selects a drink that is sold out, a message should be displayed indicating so.
In the application’s code, create a structure that has fields for the following data:
Drink name
Drink cost
Number of drinks in machine
The program should create an array of five structure objects. Each element of the array should keep data for a specific type of soft drink.
I can't figure out how to make my buttons work to decrement the quantity labels and then add each click to the label total. Please help.
Public Class Form1
' Class-level declarations
Const intMAX_SUBSCRIPT As Integer = 4 ' Upper subscript
Dim strProdNames(intMAX_SUBSCRIPT) As String ' Product Names
Dim decPrice(intMAX_SUBSCRIPT) As Decimal ' Drink Price
Dim intProdNums(intMAX_SUBSCRIPT) As Integer ' Product Numbers
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' Initialize the arrays with the product data.
InitArrays()
End Sub
Private Sub InitArrays()
' Initialize the arrays.
' First Product
strProdNames(0) = "Cola"
decPrice(0) = 1D
intProdNums(0) = 20
' Second Product
strProdNames(1) = "Root Beer"
decPrice(1) = 1D
intProdNums(1) = 20
' Third Product
strProdNames(2) = "Lemon Lime"
decPrice(2) = 1D
intProdNums(2) = 20
' Fourth Product
strProdNames(3) = "Grape Soda"
decPrice(3) = 1.5D
intProdNums(3) = 20
' Fifth Product
strProdNames(4) = "Cream Soda"
decPrice(4) = 1.5D
intProdNums(4) = 20
End Sub
Private Sub btnCola_Click(sender As Object, e As EventArgs) Handles btnCola.Click
Dim intCount As Integer = 20 ' Loop Counter
intCount -= 1 ' Decrement drink count
If intCount > 0 Then
lblTotal.Text = decPrice(0).ToString("c")
End If
End Sub

Answer 1

You need to decrement the cola count, which is in the array.
Private Sub btnCola_Click(sender As Object, e As EventArgs)
If intProdNums(0) > 0 Then
intProdNums(0)-=1 ' decrement cola drink count
End If
' show results here...
End Sub