How To Sort Algorithms for Numeric Arrays

This article demonstrates how to use sort algorithms for sorting numeric arrays. It describes three methods of sorting a series of numbers and provides sample code that shows how to implement them with the time taken to sort by each algorithm.

It is often necessary to sort a series of numbers in code, and there are various sorting algorithms available to do this.

This article includes three methods:

• Bubble sort
• Selection sort
• Shell sort

Each routine simply receives an array full of numbers within the bounds of a LONG datatype, although this could be easily changed for different numeric datatypes. Note that the sort routines return the result of the sort operation in the array that is passed to the routine. Therefore, if you do not want the original array to be modified, copy the array to a variant, as shown in the example below, and then pass the variant to the relevant procedure.

Step-by-Step Example

1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Place a CommandButton (Command1) onto Form1.
3. Add the following code in the code window of Form1:

   Option Explicit
   
   Dim startTime As Double
   Dim endTime As Double
   Dim timeToSort As Double
   Dim timeTaken As String
   
   Sub Command1_Click()
     Dim lMyArray(0 To 2000) As Long
     Dim vTemp1 As Variant
     Dim vTemp2 As Variant
     Dim vTemp3 As Variant
     Dim iLoop As Integer
    
     Randomize
     For iLoop = LBound(lMyArray) To UBound(lMyArray)
       lMyArray(iLoop) = Int(Rnd * 100) + 1
     Next iLoop
     vTemp1 = lMyArray
     vTemp2 = lMyArray
     vTemp3 = lMyArray
     Screen.MousePointer = vbHourglass
     Call BubbleSortNumbers(vTemp1)
     Call SelectionSortNumbers(vTemp2)
     Call ShellSortNumbers(vTemp3)
     Screen.MousePointer = vbDefault
     MsgBox timeTaken
   End Sub
   
   Sub BubbleSortNumbers(iArray As Variant)
     Dim lLoop1 As Long
     Dim lLoop2 As Long
     Dim lTemp As Long
     
     startTime = Time()
     For lLoop1 = UBound(iArray) To LBound(iArray) Step -1
       For lLoop2 = LBound(iArray) + 1 To lLoop1
         If iArray(lLoop2 - 1) > iArray(lLoop2) Then
           lTemp = iArray(lLoop2 - 1)
           iArray(lLoop2 - 1) = iArray(lLoop2)
           iArray(lLoop2) = lTemp
         End If
       Next lLoop2
     Next lLoop1
     endTime = Time()
     timeToSort = endTime - startTime
     timeTaken = "Bubble Sort: " & timeToSort
   End Sub
   
   Sub SelectionSortNumbers(vArray As Variant)
     Dim lLoop1 As Long
     Dim lLoop2 As Long
     Dim lMin As Long
     Dim lTemp As Long
   
     startTime = Time()
     For lLoop1 = LBound(vArray) To UBound(vArray) - 1
       lMin = lLoop1
         For lLoop2 = lLoop1 + 1 To UBound(vArray)
           If vArray(lLoop2) < vArray(lMin) Then lMin = lLoop2
         Next lLoop2
         lTemp = vArray(lMin)
         vArray(lMin) = vArray(lLoop1)
         vArray(lLoop1) = lTemp
     Next lLoop1
     endTime = Time()
     timeToSort = endTime - startTime
     timeTaken = timeTaken & ";   Selection Sort: " & timeToSort
   End Sub
   
   Sub ShellSortNumbers(vArray As Variant)
     Dim lLoop1 As Long
     Dim lHold As Long
     Dim lHValue As Long
     Dim lTemp As Long
   
     startTime = Time()
     lHValue = LBound(vArray)
     Do
       lHValue = 3 * lHValue + 1
     Loop Until lHValue > UBound(vArray)
     Do
       lHValue = lHValue / 3
       For lLoop1 = lHValue + LBound(vArray) To UBound(vArray)
         lTemp = vArray(lLoop1)
         lHold = lLoop1
         Do While vArray(lHold - lHValue) > lTemp
           vArray(lHold) = vArray(lHold - lHValue)
           lHold = lHold - lHValue
           If lHold < lHValue Then Exit Do
         Loop
         vArray(lHold) = lTemp
       Next lLoop1
     Loop Until lHValue = LBound(vArray)
     endTime = Time()
     timeToSort = endTime - startTime
     timeTaken = timeTaken & ";   Shell Sort: " & timeToSort
   End Sub
   					

4. Run the project, and click Command1. You receive the following output or similar:

   Bubble Sort: 4.6296E -05; Selection Sort: 3.4722E -05; Shell Sort: 0
   						

NOTE: In most cases, the Shell sort is the fastest of the three sorts presented. To determine which sort is faster, you can also use the QueryPerformanceCounter function to time the application code.

For additional information on how to use the QueryPerformanceCounter function, click the article number below to view the article in the Microsoft Knowledge Base: