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http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMSMethod 1: Selection Sort
Although a Selection Sort is among the easier of sorts to program, it tends to run more slowly than the Bubble Sort on large arrays of data.
To perform a Selection Sort of an array with between 1 to n number of elements, locate the largest element from 1 to n. If this is not element n, exchange the largest element with element n. Then, locate the largest element from 1 to n-1 and, if this is not element n-1, exchange the largest element with element n-1. Next, locate the largest element from 1 to n-2 and, if this is not element n-2, exchange the largest element with element n-2, and so on.
The following is an example of a Selection Sort with a Visual Basic Variant type array.
- Type or paste the following in a module sheet:
Option Base 1
Function SelectionSort(TempArray As Variant)
Dim MaxVal As Variant
Dim MaxIndex As Integer
Dim i, j As Integer
' Step through the elements in the array starting with the
' last element in the array.
For i = UBound(TempArray) To 1 Step -1
' Set MaxVal to the element in the array and save the
' index of this element as MaxIndex.
MaxVal = TempArray(i)
MaxIndex = i
' Loop through the remaining elements to see if any is
' larger than MaxVal. If it is then set this element
' to be the new MaxVal.
For j = 1 To i
If TempArray(j) > MaxVal Then
MaxVal = TempArray(j)
MaxIndex = j
End If
Next j
' If the index of the largest element is not i, then
' exchange this element with element i.
If MaxIndex < i Then
TempArray(MaxIndex) = TempArray(i)
TempArray(i) = MaxVal
End If
Next i
End Function
Sub SelectionSortMyArray()
Dim TheArray As Variant
' Create the array.
TheArray = Array(15, 8, 11, 7, 33, 4, 46, 19, 20, 27, 43, 25, 36)
' Sort the Array and display the values in order.
SelectionSort TheArray
For i = 1 To UBound(TheArray)
MsgBox TheArray(i)
Next i
End Sub
- To run the macro, click the Tools menu, point to Macro, and then click Macros.
- Select the SelectionSortMyArray macro, and then click Run.
Method 2: Bubble Sort
A Bubble Sort is more difficult to program than the Selection Sort, but it tends to run faster and more efficiently with larger arrays of data.
To perform a Bubble Sort, evaluate 1 to n-1 elements in the array where you
compare each element with the one after it (in other words, element 1 is compared to element 2, element 2 is compared to element 3, and so on). If an element is larger than the element after it, those two elements are exchanged. Continue this process until there are no more exchanges of elements. The following is an example of a Bubble Sort with a Visual Basic Variant type array.
- Type or paste the following code in a module sheet:
Option Base 1
Function BubbleSort(TempArray As Variant)
Dim Temp As Variant
Dim i As Integer
Dim NoExchanges As Integer
' Loop until no more "exchanges" are made.
Do
NoExchanges = True
' Loop through each element in the array.
For i = 1 To UBound(TempArray) - 1
' If the element is greater than the element
' following it, exchange the two elements.
If TempArray(i) > TempArray(i + 1) Then
NoExchanges = False
Temp = TempArray(i)
TempArray(i) = TempArray(i + 1)
TempArray(i + 1) = Temp
End If
Next i
Loop While Not (NoExchanges)
End Function
Sub BubbleSortMyArray()
Dim TheArray As Variant
' Create the array.
TheArray = Array(15, 8, 11, 7, 33, 4, 46, 19, 20, 27, 43, 25, 36)
' Sort the Array and display the values in order.
BubbleSort TheArray
For i = 1 To UBound(TheArray)
MsgBox TheArray(i)
Next i
End Sub
- To run the macro, click the Tools menu, point to Macro, and then click Macros.
- Select the SelectionSortMyArray macro, and then click Run.
NOTE: Both of these examples sort in ascending order. To perform a
Selection Sort in descending order, change ">" to "<" in the following line of the
SelectionSort function:
If TempArray(j) > MaxVal Then
To perform a Bubble Sort in descending order, change ">" to a "<" in the following line of the
BubbleSort function:
If TempArray(i) > TempArray(i + 1) Then