FindBin

Function BinarySearch(Lower As Integer, Upper As Integer, _
Target As String) As Integer
'// Vars "Lower" and "Upper" refer to the Lower and Upper

'// indices of the array being searched. "Target" is, of course,

'// our target. When initially calling this function you should always

'// specify Lower = Lbound(DataArray) and Upper = Ubound(DataArray)to include

'// the entire array. The function returns the index of thet Target.

'// This function only works correctly if you have a SORTED array of data. This can

'// be easily accomplished with a sorted list box control. Considering the maximum of

'// 32,768 items a listbox control can handle, this funct will need to only make 16 passes to

'// Find the Target item. This Function does not match partial strings.


Dim Middle As Integer '// Index of middle element
'// First we check the middle element in the

'array to see if it is = to or <> our target

Middle = Fix(Lower + Upper) / 2 '// Fix returns everything
'// before the Decimal i.e. 9.98 = 9...this

'line only returns the middle element index

If DataArray(Middle) = Target Then '// We found our String in the middle of the list
BinarySearch = Middle '// Return the index of the hit
Exit Function '// Job done. Gone home.
End If
If Lower >= Upper Then '// The list has been reduced
(or is only)a Single element. Search failed.
BinarySearch = -1 '// Return "-1" If Target has Not been found
Exit Function '// Job done. Gone home.
End If
If Target < DataArray(Middle) Then '// Depending on if
'//the binary value of the middle element is

'greater or less than the binary value of the

'Target we can either discard the upper or lower

'half of the [remaining]list.

Upper = Middle + 1 '// Discard Upper half of list
Else
Lower = Middle + 1 '// Discard Lower half of list
End If
'// if we get to this point, we have not found

'the Target and we still have itemsin the list,

'so we call the function again (recursively)

'with revised parms...

BinarySearch = BinarySearch(Lower, Upper, Target)
End Function