下面这段代码，是我用来计算每个月存500元进银行，连续30年，最后连本带利能有多少钱。这里面涉及复利计算。界面中右边的文本框用来输出每一次计算的结果。
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Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim nianxian As Integer '年限变量
Dim dingcun As Integer '定存变量
Dim fuli_big As Long '大复利
Dim fuli_small As Long '小复利
Dim i As Integer '循环变量
Dim DATAstring As String '数据字符串
nianxian = Val(年限_TextBox.Text)
dingcun = Val(定存_TextBox.Text)
DATAstring = ""
For i = 1 To nianxian
fuli_small = dingcun * (1 + 0.1875)
dingcun = fuli_small
fuli_big = fuli_big + fuli_small
DATAstring = DATAstring + "[" + Trim(Str(i)) + "]" + Str(fuli_big) + Chr(13) + Chr(10)
'DATAstring = DATAstring + "[" + Trim(Str(i)) + "]" + Str(fuli_small) + Chr(13) + Chr(10)
Next
'fuli_big = fuli_small
TextBox1.Text = DATAstring
结果_TextBox.Text = Str(fuli_big) + "元"
End Sub
用vb.net做的校友录……（附所有源代码）
来源：不详 作者 佚名 点击数：31 录入时间：07-12-17 15:21:39
想必大家都上过校友录吧，里面的功能虽然不是很强大，但是为我们这些毕业之后各奔西东的学子来说，到真是提供了一个好的聚集点，下面是我用vb.net做的校友录，当然也不能说是校友录了，只能说是我们班的学友录了：）不过只要你掌握了这种编程思想，校友录就不在话下了。这里我将重点谈一下关于管理员权限赋予。
以前有这个想法的时候，难就难在管理员身份的赋予上，开始想如果一般用户在被提升为管理员之后，我可以把他的信息转到另外一个表中，以后登陆的时候先检查manage表中是否有他就行了，这种办法我已经实现了，是不是有些笨……可是正在我要正式开工的时候，一个想法突然冒了出来，是什么呢？呵呵，就是在数据库中再增加一个字段了如果是第一次注册就让这个字段item(int)的值为0，要是被提升之后就update为1，班级创始人呢？当然了，在他申请时付给他一个班级id，然后先判断班级id为这个已经注册的人信息条数是否为0，如果是，那么就付给他item=2好了。下面的代码中，我没有实现这个功能，因为我做的是班友录的，当然了，我就是管理员喽：）
在这里，我使用的是checkboxlist(两个)，一个用来转换数据（visibe=fause），一个用来显示数据，还有一个checkbox用来写全部选中的事件。当然了还有两个按钮事件，一个是用来提升为管理员的，一个是用来降级为一般用户的，这两个按钮在判断为一般用户时
enable都是为fause的，只有当判断登录为管理员时才为true。当然了，如果你是班级创始人，是不可能被降级的：）
这里用来显示信息的我用的是一个datagrid，当判断为非管理员时，删除栏的visible将为fause，为管理员的时候，才为true，也就是说只有管理员才可以删除信息。而不是注册的用户是不能发言的所有的按钮控件的enable将都为fause。
代码如下：board.aspx
%@ Page Language="vb" AutoEventWireup="false" Codebehind="boaman.aspx.vb" Inherits="_99re1.boaman"%
!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
HTML
HEAD
title/title
meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR"
meta content="Visual Basic 7.0" name="CODE_LANGUAGE"
meta content="javascript" name="vs_defaultClientScript"
meta content="" name="vs_targetSchema"
/HEAD
body background="image/bg.gif" MS_POSITIONING="GridLayout"
form id="Form1" method="post" runat="server"
asp:checkbox id="yourcheck" style="Z-INDEX: 101; LEFT: 84px; POSITION: absolute; TOP: 71px" runat="server" Text="全部选中" AutoPostBack="True" ForeColor="SaddleBrown" Font-Bold="True"/asp:checkbox
asp:button id="Button1" style="Z-INDEX: 102; LEFT: 34px; POSITION: absolute; TOP: 43px" runat="server" Text="提升为管理员" Height="20px" Width="100px" BackColor="Gainsboro" BorderColor="Lavender" BorderWidth="2px" BorderStyle="Outset"/asp:button
asp:button id="Button2" style="Z-INDEX: 103; LEFT: 142px; POSITION: absolute; TOP: 43px" runat="server" Text="降级为一般用户" Height="20px" Width="100px" BackColor="Gainsboro" BorderColor="Lavender" BorderWidth="2px" BorderStyle="Outset"/asp:button
asp:checkboxlist id="CheckBoxList1" style="Z-INDEX: 104; LEFT: 14px; POSITION: absolute; TOP: 10px" runat="server" Visible="False"/asp:checkboxlist
asp:checkboxlist id="mycheck" style="Z-INDEX: 105; LEFT: 98px; POSITION: absolute; TOP: 99px" runat="server" ForeColor="Navy" Font-Size="X-Small"/asp:checkboxlist
asp:label id="Label1" style="Z-INDEX: 106; LEFT: 82px; POSITION: absolute; TOP: 14px" runat="server" ForeColor="Red" Font-Names="方正姚体"（已注册用户）/asp:label
asp:image id="Image1" style="Z-INDEX: 107; LEFT: 260px; POSITION: absolute; TOP: 180px" runat="server" Height="124px" Width="221px" ImageUrl="image/99re1-1.gif"/asp:image
asp:datagrid id="DataGrid1" style="Z-INDEX: 108; LEFT: 250px; POSITION: absolute; TOP: 83px" runat="server" Height="113px" Width="461px" BorderColor="#ffcc66" AutoGenerateColumns="False" HeaderStyle-Font-Size="9" HeaderStyle-HorizontalAlign="Center" HeaderStyle-ForeColor="red" HeaderStyle-Font-Bold="True"
Columns
asp:HyperLinkColumn ItemStyle-ForeColor="navy" ItemStyle-HorizontalAlign="Center" ItemStyle-Height="24" ItemStyle-Font-Size="9" DataNavigateUrlField="stu_id" DataNavigateUrlFormatString="querry.aspx?stu_id={0}" DataTextField="stu_id" HeaderText="学号"/asp:HyperLinkColumn
asp:BoundColumn ItemStyle-ForeColor="navy" ItemStyle-HorizontalAlign="Center" ItemStyle-Width="100" ItemStyle-Font-Size="9" DataField="tel" HeaderText="电话"/asp:BoundColumn
asp:BoundColumn ItemStyle-ForeColor="navy" ItemStyle-HorizontalAlign="Center" ItemStyle-Width="80" ItemStyle-Font-Size="9" DataField="oicq" HeaderText="OICQ"/asp:BoundColumn
asp:BoundColumn ItemStyle-ForeColor="navy" ItemStyle-HorizontalAlign="Center" ItemStyle-Width="140" ItemStyle-Font-Size="9" DataField="email" HeaderText="E-mail"/asp:BoundColumn
asp:BoundColumn ItemStyle-ForeColor="navy" ItemStyle-HorizontalAlign="Center" ItemStyle-Width="60" ItemStyle-Font-Size="9" DataField="point" HeaderText="登录次数"/asp:BoundColumn
/Columns
/asp:datagrid
/form
/body
/HTML
下面是codebehind中的内容：boaman.asp.vb
Imports System.Data
Imports System.Data.SqlClient
Public Class boaman
Inherits System.Web.UI.Page
Protected WithEvents yourcheck As System.Web.UI.WebControls.CheckBox
Protected WithEvents Button1 As System.Web.UI.WebControls.Button
Protected WithEvents CheckBoxList1 As System.Web.UI.WebControls.CheckBoxList
Protected WithEvents mycheck As System.Web.UI.WebControls.CheckBoxList
Protected WithEvents Label1 As System.Web.UI.WebControls.Label
Protected WithEvents Image1 As System.Web.UI.WebControls.Image
Protected WithEvents DataGrid1 As System.Web.UI.WebControls.DataGrid
Protected WithEvents Button2 As System.Web.UI.WebControls.Button
#Region " Web Form Designer Generated Code "
'This call is required by the Web Form Designer.
System.Diagnostics.DebuggerStepThrough() Private Sub InitializeComponent()
End Sub
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub
#End Region
Dim conn As SqlConnection = New SqlConnection("server=lixinri;uid=sa;pwd=;database=99re1")
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'////////////////////判断是否为过客
If Session("stu_id") = "" Then
Button1.Enabled = False : Button2.Enabled = False
'////////////////////调用check()事件
check()
Else
If Not IsPostBack Then
Dim sql As String = "select * from pwd where stu_id=@stu_id"
Dim comm As SqlCommand = New SqlCommand(sql, conn)
comm.Parameters.Add(New SqlParameter("@stu_id", SqlDbType.Int, 4))
comm.Parameters("@stu_id").Value = Session("stu_id")
Dim dr As SqlDataReader
conn.Open()
dr = comm.ExecuteReader
While dr.Read
If dr.Item("term") = "0" Then
'///////////////////判断是否为一般用户
dr.Close()
Button1.Enabled = False : Button2.Enabled = False
Dim sql_1 As String = "select a.stu_id as stu_id,a.term,b.name as name,b.tel as tel,b.call as oicq,b.point as point,b.email from pwd a,stu_base b where a.stu_id=b.stu_id"
Dim cmd As New SqlCommand(sql_1, conn)
dr = cmd.ExecuteReader
While dr.Read
If dr.Item("term") = "1" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=darkorange(管理员)/font")
ElseIf dr.Item("term") = "2" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=red(班级创始人)font")
Else
mycheck.Items.Add("u" dr.Item("name") "/u")
End If
CheckBoxList1.Items.Add(dr.Item("stu_id"))
End While
Else
'////////////////////判断是否为管理员
dr.Close()
Button1.Enabled = True : Button2.Enabled = True
Dim sql_1 As String = "select a.stu_id as stu_id,a.term,b.name as name,b.tel as tel,b.call as oicq,b.point as point,b.email from pwd a,stu_base b where a.stu_id=b.stu_id"
Dim cmd As New SqlCommand(sql_1, conn)
dr = cmd.ExecuteReader
While dr.Read
If dr.Item("term") = "1" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=darkorange(管理员)/font")
ElseIf dr.Item("term") = "2" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=red(班级创始人)font")
Else
mycheck.Items.Add("u" dr.Item("name") "/u")
End If
CheckBoxList1.Items.Add(dr.Item("stu_id"))
End While
End If
End While
dr.Close()
'////////////////////////取出数据，填充dataset
Dim mysql As String = "select a.stu_id as stu_id,a.term,b.name as name,b.tel as tel,b.call as oicq,b.point as point,b.email from pwd a,stu_base b where a.stu_id=b.stu_id"
comm = New SqlCommand(mysql, conn)
Dim mycomm As SqlDataAdapter = New SqlDataAdapter(mysql, conn)
Dim ds As DataSet = New DataSet()
mycomm.Fill(ds, "base")
DataGrid1.DataSource = ds.Tables("base").DefaultView
DataGrid1.DataBind()
End If
End If
End Sub
'///////////////////////书写check()事件
Sub check()
If Not IsPostBack Then
Dim mysql As String = "select a.stu_id as stu_id,a.term,b.name as name,b.tel as tel,b.call as oicq,b.point as point,b.email from pwd a,stu_base b where a.stu_id=b.stu_id"
Dim comm As New SqlCommand(mysql, conn)
Dim dr As SqlDataReader
conn.Open()
dr = comm.ExecuteReader
While dr.Read
If dr.Item("term") = "1" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=darkorange(管理员)/font")
ElseIf dr.Item("term") = "2" Then
mycheck.Items.Add("u" dr.Item("name") "/u" "font color=red(班级创始人)font")
Else
mycheck.Items.Add("u" dr.Item("name") "/u")
End If
CheckBoxList1.Items.Add(dr.Item("stu_id"))
End While
dr.Close()
Dim mycomm As SqlDataAdapter = New SqlDataAdapter(mysql, conn)
Dim ds As DataSet = New DataSet()
mycomm.Fill(ds, "base")
DataGrid1.DataSource = ds.Tables("base").DefaultView
DataGrid1.DataBind()
End If
End Sub
'/////////////////////填充yourcheck
Private Sub yourcheck_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles yourcheck.CheckedChanged
Dim i As Integer
For i = 0 To mycheck.Items.Count - 1
If yourcheck.Checked Then
mycheck.Items(i).Selected = True
Else
mycheck.Items(i).Selected = False
End If
Next
End Sub
'///////////////////////提升一般用户为管理员
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
conn.Open()
Dim i As Integer
For i = 0 To mycheck.Items.Count - 1
If mycheck.Items(i).Selected Then
Dim sql_1 As String = "update pwd set term=1 where stu_id=@stu_id and term=0"
Dim comm As SqlCommand = New SqlCommand(sql_1, conn)
comm.Parameters.Add(New SqlParameter("@stu_id", SqlDbType.Int, 4))
comm.Parameters("@stu_id").Value = CheckBoxList1.Items(i).Text
comm.ExecuteNonQuery()
End If
Next
Response.Redirect("boaman.aspx")
End Sub
'///////////////////////降级管理员为一般用户
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
conn.Open()
Dim i As Integer
For i = 0 To mycheck.Items.Count - 1
If mycheck.Items(i).Selected Then
Dim sql_1 As String = "update pwd set term=0 where stu_id=@stu_id and term=1"
Dim comm As SqlCommand = New SqlCommand(sql_1, conn)
comm.Parameters.Add(New SqlParameter("@stu_id", SqlDbType.Int, 4))
comm.Parameters("@stu_id").Value = CheckBoxList1.Items(i).Text
comm.ExecuteNonQuery()
End If
Next
Response.Redirect("boaman.aspx")
End Sub
End Class
当然了，这里面还有好多不足的地方，恳求高手批评指正。
校友录还有一些其它的功能就很简单了，这里就不再探讨了。
Dim url As String=" 网址"
Dim httpReq As System.Net.HttpWebRequest
Dim httpResp As System.Net.HttpWebResponse
Dim httpURL As New System.Uri(url)
httpReq = CType(WebRequest.Create(httpURL), HttpWebRequest)
httpReq.Method = "GET"
httpResp = CType(httpReq.GetResponse(), HttpWebResponse)
httpReq.KeepAlive = False ' 获取或设置一个值，该值指示是否与
Internet资源建立持久连接。
Dim reader As StreamReader = _
New StreamReader(httpResp.GetResponseStream,
System.Text.Encoding.GetEncoding(-0))
Dim respHTML As String = reader.ReadToEnd() 'respHTML就是网页源代码
这个要看扫描枪的通讯接口和通讯协议，以及接口程序是否支持VB.NET等。
用PDF417动态库可生成2维条码
阅读直接用2维条码扫描枪即可读出数据，然后还原数据
有个二维条码演示应用小软件，可参考