More efficient Bubble Sort

Category:

C#, VB.NET, ASP.NET

Type:

Snippets

Difficulty:

Intermediate

Author:

Anonymous

Version Compatibility: Visual Basic 6

More information:

This is Joel's Bubble Sort Function, revised only slightly for efficiency. The first pass through the loop places the smallest value in position (lStart). Pass 2 places the next smallest (or equal) value in position (lStart+1). The addition of counter "lPass" eliminates wasted iterations of the For - Next loop.

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
' (None)

Code:

Public Function BubbleSortArray(ByVal NumericArray As Variant) _
    As Variant

'RETURNS Array, or vbEmpty if there's an error
'e.g., passed array contains elements that
'can't be compared to each other, such as
'objects

'will work when elements are all numbers or single characters
'of the same case.

Dim vAns As Variant
Dim vTemp As Variant
Dim bSorted As Boolean
Dim lCtr As Long
Dim lCount As Long
Dim lStart As Long
Dim lPass as long

vAns = NumericArray
 
If Not IsArray(vAns) Then
    BubbleSortArray = vbEmpty
    Exit Function
End If

On Error GoTo ErrorHandler

lStart = LBound(vAns)
lCount = UBound(vAns)
lPass=0

bSorted = False
   
    Do While Not bSorted
      bSorted = True

For lCtr = lCount - 1 To lStart + lPass Step -1
        If vAns(lCtr + 1) < vAns(lCtr) Then
          DoEvents
          bSorted = False
           vTemp = vAns(lCtr)
           vAns(lCtr) = vAns(lCtr + 1)
           vAns(lCtr + 1) = vTemp
         End If
      Next lCtr
      lPass = lPass + 1
    Loop
    
BubbleSortArray = vAns
Exit Function

ErrorHandler:
BubbleSortArray = vbEmpty
Exit Function
End Function