[RESOLVED] Help with simple Array program

I got this from a book.:
Forty students were asked to rate the quality of the food in the student cafeteria on a scale of 1 to 10 (1 means awful and 10 means excellent). Place the 40 responses in an Integer array and summarize the results of the poll.

The form has a command button named cmdPrint. Here is the code:

Code:

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Option Explicit
Option Base 1
Dim mResponses(40) As Integer

Private Sub Form_Load()
 Dim x As Integer
 
 For x = LBound(mResponses) To UBound(mResponses)
  mResponses(x) = 1 + Int(Rnd * 10)
 Next x
End Sub

Private Sub cmdPrint_Click()
 Dim frequency(10) As Integer '10 elements
 Dim x As Integer
 
 Call Cls
 Call Randomize
 
 'Calculate results
 For x = LBound(mResponses) To UBound(mResponses)
  frequency(mResponses(x)) = frequency(mResponses(x)) + 1
 Next x
 Print "Rating" & Space(3) & "Frequency"
 For x = LBound(frequency) To UBound(frequency)
  Print Space(3) & x & vbTab & vbTab & frequency(x)
 Next x
 cmdPrint.Enabled = False
End Sub

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I don't understand the logic of this line:
frequency(mResponses(x)) = frequency(mResponses(x)) + 1
I've read the book's explanation over and over but I still don't get it.
Here is what the book says: "This statement increments the appropriate frequency counter depending on the value of mResponses(x). For example, when the counter x is 1, mResponses(x) is 1, so frequency(mResponses(x) is actually interpreted as frequency(1) = frequency(1) + 1 which increments array index one...." I don't understand it! How does this statement calculate the frequency of a response??

Many thanks guys!!!

Hello,

I suggest you use the "edit" button and use

Code:

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  CODE before your code and  /CODE at its End (both in between brackets "[]"

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, please, so, that it would be readable.. (do it please)

frequency(mResponses(x)) = frequency(mResponses(x)) + 1
as you randomize 10, you can get 10 !
but Dim frequency(10) means 10 élementy i.e 0;1;2,3,4,5,6,7,8,9
No 10 !

Quote:

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Originally Posted by moa

but Dim frequency(10) means 10 élementy i.e 0;1;2,3,4,5,6,7,8,9
No 10 !

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Option Base 1 means that that Dim statement makes an array that goes from 1 to 10.
Even Option Base 0 would have an index of 10 in that array, but you'd have 11 items (from 0 to 10).

My suggestion, even if you use Option Base, explicitly define the size of arrays, like so:

Code:

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Dim frequency(1 To 10) As Integer

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@sbstn26:
The line of code:

Code:

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frequency(mResponses(x)) = frequency(mResponses(x)) + 1

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It increments the counter for that value.

The array frequency has an index of 1 to 10. That index corresponds to the ratings that can be given. That description you have means that the frequency array is used to store the number of times each rating is given.

That example is poor, though.

Code:

---

Option Explicit
Option Base 1
Dim mResponses(40) As Integer

Private Sub Form_Load()
    Dim x As Integer
   
    Call Randomize '<-- Where this should be called, since it makes the results random now
   
    For x = LBound(mResponses) To UBound(mResponses)
        mResponses(x) = 1 + Int(Rnd * 10)
    Next x
End Sub

Private Sub cmdPrint_Click()
    Dim frequency(10) As Integer '10 elements
    Dim x As Integer
   
    Call Cls
    'Call Randomize '<-- No reason to do this here, Rnd isn't called in this Sub at all
   
    'Calculate results
    For x = LBound(mResponses) To UBound(mResponses)
        frequency(mResponses(x)) = frequency(mResponses(x)) + 1
    Next x
    Print "Rating" & Space(3) & "Frequency"
    For x = LBound(frequency) To UBound(frequency)
        Print Space(3) & x & vbTab & vbTab & frequency(x)
    Next x
End Sub

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The above is corrected, but if you don't want to restart each time, use this instead:

Code:

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Option Explicit
Option Base 1
Dim mResponses(40) As Integer

Private Sub cmdPrint_Click()
    Dim frequency(10) As Integer '10 elements
    Dim x As Integer
   
    Call Randomize
    Call Cls
   
    For x = LBound(mResponses) To UBound(mResponses)
        mResponses(x) = 1 + Int(Rnd * 10)
    Next x
   
    'Calculate results
    For x = LBound(mResponses) To UBound(mResponses)
        frequency(mResponses(x)) = frequency(mResponses(x)) + 1
    Next x
    Print "Rating  Frequency"
    For x = LBound(frequency) To UBound(frequency)
        Print Space$(3) & x & vbTab & vbTab & frequency(x)
    Next x
End Sub

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