二分法查找

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim flag = 0
        Dim test() As Integer = {10, 11, 12, 16, 18, 23, 29, 33, 48, 54, 57, 68, 77, 84, 98}
        Dim key = TextBox1.Text
        Dim lo As Integer = 0
        Dim hi As Integer = test.Length - 1
        While (lo <= hi)
            Dim mid As Integer = lo + (hi - lo) / 2
            If key < test(mid) Then
                hi = mid - 1
            ElseIf key > test(mid) Then
                lo = mid + 1
            Else
                MsgBox("数据存放在第" & mid & "位")
                flag = 1
                Exit While
            End If
        End While
        If flag <> 1 Then
            MsgBox("数据未在数组中")
        End If
    End Sub

End Class