CODEWITHSUNDEEP
arraysvb.netsorting
Marcel
Marcel

Reputation: 159

Bubble sort index was outside the bounds of the array

Public Class Form3
Public Swapped As Boolean
Public ComparisonNumber As Integer
Dim Temp As String
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    Swapped = True
    While Swapped = True
        Swapped = False
        ComparisonNumber = 0
        While ComparisonNumber < PatientCount
            If Names(ComparisonNumber) > Names(ComparisonNumber + 1) Then
                Temp = Names(ComparisonNumber)
                Names(ComparisonNumber) = Names(ComparisonNumber + 1)
                Names(ComparisonNumber + 1) = Temp
                Swapped = True
            End If
            ComparisonNumber = ComparisonNumber + 1
        End While
    End While

    For i = 0 To PatientCount
        lstPatientNames.Items.Add(Names(i))
        lstPatientHeights.Items.Add(Heights(i))
        lstPatientWeights.Items.Add(Weights(i))
    Next

End Sub
End Class

This is the code for my bubble sort for a project but when I press the button that sorts and displays the array I get the error: "index was outside the bounds of the array" on the line

If Names(ComparisonNumber) > Names(ComparisonNumber + 1) Then

Any ideas as to why? Thanks

Upvotes: 0

Views: 110

Answers (1)

Damien_The_Unbeliever
Damien_The_Unbeliever

Reputation: 239764

If PatientCount is the number of items being stored in Names (you've not shown the definition for either of these) then the indexes for Names run from 0 to PatientCount - 1.

So, in the last iteration, when ComparisonNumber is equal to PatientCount - 1, you attempt to access the items at indexes PatientCount - 1 and PatientCount - but that second index is invalid.

Swapped = True
While Swapped = True
    Swapped = False
    ComparisonNumber = 0
    While ComparisonNumber < PatientCount - 1 'Changed here
        If Names(ComparisonNumber) > Names(ComparisonNumber + 1) Then
            Temp = Names(ComparisonNumber)
            Names(ComparisonNumber) = Names(ComparisonNumber + 1)
            Names(ComparisonNumber + 1) = Temp
            Swapped = True
        End If
        ComparisonNumber = ComparisonNumber + 1
    End While
End While

For i = 0 To PatientCount - 1 'And here
    lstPatientNames.Items.Add(Names(i))
    lstPatientHeights.Items.Add(Heights(i))
    lstPatientWeights.Items.Add(Weights(i))
Next

Also, these lines seem wrong:

    lstPatientHeights.Items.Add(Heights(i))
    lstPatientWeights.Items.Add(Weights(i))

Because you haven't been sorting Heights and Weights in the same way that you have been sorting Names, so they're going to still be in their original order. You either should be performing the same swaps to all of these when you decide to perform a swap, or you ought to be storing objects in a single (array?) that have 3 properties - Name, Height and Weight and then be swapping these objects.

Upvotes: 2

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