Computer Programming Concepts and Visual Basic David I. Schneider

EXAMPLE 5
In the following program the array firm( ) contains the alphabetized names of up to 100 corporations. The
program requests the name of a corporation as input and uses a binary search to determine whether or not
the corporation is in the array.
Dim firm(1 TO 100) As String
Dim numFirms As Integer
Private Sub BinarySearch(corp As String, result As String)
Dim foundFlag As Boolean
Dim first As Integer, middle As Integer, last As Integer
‘Array firm() assumed already ordered alphabetically
‘Binary search of firm() for corp
foundFlag = False
first = 1
last = numFirms
Do While (first corp
last = middle - 1
Case Is <
corp first = middle + 1
End Select
Loop
If foundFlag Then
result = “found”
Else
result = “not found”
End If
End Sub
Private Sub cmdSearch_Click()
Dim corp As String, result As String
corp = UCase(Trim(txtCorporation.Text))
Call BinarySearch(corp, result)
‘Display results of search
picResult.Cls
picResult.Print corp; “ ”; result
End Sub
Private Sub Form_Load()
‘Fill array with data from FIRMS.TXT
Open “FIRMS.TXT” For Input As #1 ‘Contains up to 100 companies
numFirms = 0
Do While (Not EOF(1)) And (numFirms < UBound(firm))
numFirms = numFirms + 1
Input #1, firm(numFirms)
Loop Close #1
End Sub
Sorting and Searching 193