FILE: How to Sort Algorithms for Numeric Arrays

• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0
• Standard, Professional, and Enterprise Editions of Microsoft Visual Basic, 16-bit and 32-bit, for Windows, version 4.0

SUMMARY

SORTED.EXE is a sample that demonstrates how to sort algorithms for numeric arrays. This article describes the three methods of sorting a series of numbers in a code and provides sample code showing how to implement them.

The following file is available for download from the Microsoft Software Library:

 ~ Sorted.exe

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MORE INFORMATION

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

The three methods discussed are:

1. Bubble sort.

2. Selection 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 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 project. Form1 is created by default.

2. Place a CommandButton on the form.

3. Add the following code to the Form1 code window:

   Option Explicit

      sub Command1_Click()
        Dim lMyArray(0 TO 9) 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
        Call BubbleSortNumbers(vTemp1)
        Call SelectionSortNumbers(vTemp2)
        Call ShellSortNumbers(vTemp3)
      end sub
   
      Sub BubbleSortNumbers(iArray As Variant)
        Dim lLoop1 As Long
        Dim lLoop2 As Long
        Dim lTemp As Long
        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
      End Sub
   
      Sub SelectionSortNumbers(vArray As Variant)
        Dim lLoop1 As Long
        Dim lLoop2 As Long
        Dim lMin As Long
        Dim lTemp As Long
        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
      End Sub
   
      Sub ShellSortNumbers(vArray As Variant)
        Dim lLoop1 As Long
        Dim lHold As Long
        Dim lHValue As Long
        Dim lTemp As Long
        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)
      End Sub