Index was outside the bounds of the array - VB - vb.net

Question

Public Class Form1
Dim a As Integer
Dim b As Integer
Dim c As Integer
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If CheckBox1.Checked = True Then
a += 1
Else : a += 0
End If
If CheckBox2.Checked = True Then
b += 1
Else : b += 0
End If
If CheckBox3.Checked = True Then
c += 1
Else : c += 0
End If
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim max As Integer = 0
Dim d() As Integer = {a, b, c}
Dim f() As String = {"ch1", "ch2", "ch3"}
For i As Integer = 0 To 2
If max < d(i) Then
max = d(i)
Else : max = max
End If
Next
Label1.Text = f(max)
End Sub
End Class

Answer 1

So, in summary you're using checkboxes to increment numbers every time Button1 is clicked. These values are stored in variables a, b and c, which when Button2 is clicked, are put into an integer array. From the looks of your code you're then trying to find which one of these is the largest value and display a value from another array based off that index. The problem, of course, is that you're taking the value of d and using it as the index of f. The value of max then becomes an arbitrarily large number, easily exceeding the bounds of f which in your example only has three values in it. You might want to try it more like this:
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim max As Integer = 0
Dim index as Integer = 0
Dim d() As Integer = {a, b, c}
Dim f() As String = {"ch1", "ch2", "ch3"}
For i As Integer = 0 To 2
If max < d(i) Then
max = d(i)
index = i
Else : max = max
End If
Next
Label1.Text = f(index)
End Sub
This still uses max as the comparer, but takes note of the index of the For loop when it reaches a new highest number, using that to pull out the value of f, ensuring that the value of index is never higher than i.

Answer 2

The values of a,b and c are being incremented ever time you click the first button depending on their checked state. Then when you loop thru and get the max of the variables you are trying to use that as an indec into the f() array. The f() array can only go from 0 to 2 but max can be any value. You cannot use max to select from the array. What are you trying to do ?