form1.vb

来自「Visual Basic .NET程序设计教程源代码」· VB 代码 · 共 93 行

Public Class Form1
    Inherits System.Windows.Forms.Form
    '形参a()为有序数组，low、high查找下界、上界，key查找关键值
    'index返回结果，查找到关键值在数组中的下标，找不到为-1
    Sub birsearch(ByRef a(), ByVal low, ByVal high, ByVal key, ByVal index)
        Dim mid, min As Integer
        mid = (low + high) \ 2        '取查找区间的中点
        If a(mid) = key Then
            index = mid               '查找到，返回查找到的下标
            Exit Sub
        ElseIf low > high Then        '二分法查找区间无元素，查找不到
            index = -1
            Exit Sub
        End If
        If key < a(mid) Then          '查找区间在上半部
            high = min - 1
        Else
            low = mid + 1             '查找区间在下半部
        End If
        Call birsearch(a, low, high, key, index)     '递归调用查找函数
        TextBox1.Text = index
    End Sub

#Region " Windows 窗体设计器生成的代码 "

    Public Sub New()
        MyBase.New()

        '该调用是 Windows 窗体设计器所必需的。
        InitializeComponent()

        '在 InitializeComponent() 调用之后添加任何初始化

    End Sub

    '窗体重写处置以清理组件列表。
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Windows 窗体设计器所必需的
    Private components As System.ComponentModel.IContainer

    '注意：以下过程是 Windows 窗体设计器所必需的
    '可以使用 Windows 窗体设计器修改此过程。
    '不要使用代码编辑器修改它。
    Friend WithEvents Button1 As System.Windows.Forms.Button
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button
        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(8, 8)
        Me.Button1.Name = "Button1"
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Button1"
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(96, 8)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(184, 21)
        Me.TextBox1.TabIndex = 1
        Me.TextBox1.Text = ""
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.TextBox1)
        Me.Controls.Add(Me.Button1)
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region
    Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim b() = {5, 13, 19, 21, 37, 56, 64, 75, 80, 88, 92}, n As Integer
        Call birsearch(b, LBound(b), UBound(b), 21, n%)
        TextBox1.Text = n
    End Sub
End Class