VB.net的特殊语法（区别于C#.NET）

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VB.net的特殊语法（区别于C#.NET）

1:引入命名空间（Imports）

Imports System.Exception
Imports System.Data.SqlClient
Imports System.Security.Cryptography
Imports System.Text.StringBuilder

2：实例化类

Dim myConn As SqlConnection
myConn = New SqlConnection(ConnString)

3：IF THEN ELSE END块

If Not IsPostBack() Then
     txtEmployee.Text = ""
     txtPassWord.Text = ""
else
　　txtEmployee.Text = "
      txtPassWord.Text = ""
End If

4:Try catch Fanally End Try块

Try
    myConn = New SqlConnection(ConnString)
    myConn.Open()Catch ex As Exception
    Throw New Exception(ex.Message & "clsDatabaseAccess.GetDataBase()")
Finally
    myConn.Close()
    myConn = Nothing
End Try

5：Sub块

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Try
            If Not IsPostBack() Then
                txtEmployee.Text = ""
                txtPassWord.Text = ""
            End If

        Catch ex As Exception
            Response.Write(ex.Message)
        End Try
End Sub

6：函数块（function）

    Private Function ByteArrayToString(ByVal arrInput() As Byte) As String
        Dim i As Integer
        Dim sOutput As New System.Text.StringBuilder(arrInput.Length)

        For i = 0 To arrInput.Length - 1
            sOutput.Append(arrInput(i).ToString("X2"))
        Next
        Return sOutput.ToString()
    End Function

7：变量定义

        Dim bytMessage As Byte()
        Dim bytMD5 As Byte()
        Dim strMD5 As String
        Dim strPassword As String
        Dim Readlen As Integer

　　　　　'数组定义
        Dim tTfile() As String = Split(tfileN.Trim, "\")

        Dim MD5 As New      System.Security.Cryptography.MD5CryptoServiceProvider

8：数据库连接获取DS方法

WEBConfig中配置数据库连接字符串

<appSettings>
    <add key="ConnectionString" value="server=1.1.1.1; database=dbTest;user=test;password=test"></add>
</appSettings>

取得WEbCnfig中配置的特定字符串的值：

Private strConnectString = System.Configuration.ConfigurationSettings.AppSettings.Get("ConnectPassWord")

数据库连接并返回ds：

        Dim myConn As SqlConnection
        Dim myDataAdapter As SqlDataAdapter
        Dim ds As DataSet

        Try
            myConn = New SqlConnection(ConnString)
            myConn.Open()
            
           strSql = "select EmployeeManagementID from mstEmployeeBasic where EmployeeCode =" & txtEmployee.Text.Trim().ToString()
            myDataAdapter = New SqlDataAdapter(Sql, myConn)
            Dim ds As New DataSet

            myDataAdapter.Fill(ds)
            GetDataBase = ds
        
            If Not (ds.Tables(0).Rows.Count > 0) Then
                txtEmployee.Text = ""
                txtPassWord.Text = ""
            Else
                txtEmployee.Text = ""
            End If
        Catch ex As Exception
            Throw New Exception(ex.Message & "clsDatabaseAccess.GetDataBase()")

        Finally
            myConn.Close()
            myConn = Nothing
        End Try

9：后台提示信息在前台显示：

Response.Write("<script lanugage='javascript'>alert('パスワードが間違いました。');</script>")

10：后台页面跳转：

Response.Redirect("TestPaperList.aspx?code=" & StrConv(txtEmployee.Text.Trim(), VbStrConv.Narrow) & "")

11：后台取URL传过来的参数的值

            employeecode = Request.QueryString("code")
            AdminType = Request.QueryString("type")

12:在Vb.net中用me代替了this

                Me.txtCode.Text = ""
                Me.txtPassword1.Text = ""
                Me.txtPassword2.Text = ""

13:类型转换

                intCode = CInt(employeecode.Trim())
                intType = CInt(AdminType.Trim)

14：拼接数据库字符串

            strSql = ""
            strSql = strSql & "insert into                                      " & vbCrLf
            strSql = strSql & "   administrator values(                          " & vbCrLf
            strSql = strSql & "         <$code>                                  " & vbCrLf
            strSql = strSql & "        ,'<$password>'                            " & vbCrLf
            strSql = strSql & "        ,<$type>)                                  " & vbCrLf


            strSql = Replace(strSql, "<$code>", code.ToString)
            strSql = Replace(strSql, "<$password>", password.Trim.Replace("'", "''"))
            strSql = Replace(strSql, "<$type>", type.ToString)

15：For循环块

Dim i As Integer = 0
For i = 0 To dsSelectedEmployee.Tables(0).Rows.Count - 1
     lstSelected.Items(i).Text = dsSelectedEmployee.Tables(0).Rows(i)(0) & " " & dsSelectedEmployee.Tables(0).Rows(i)(1)
Next

16：下拉框绑定值

        Dim dsSelectedEmployee As DataSet

        Try
            If Me.dlstClass.SelectedIndex <> 0 Then
                dsSelectedEmployee = GetAnswerer()
                Me.lstSelected.DataValueField = "EmployeeNo"
                Me.lstSelected.DataSource = dsSelectedEmployee.Tables(0)
                Me.lstSelected.DataBind()
                Dim i As Integer = 0
                For i = 0 To dsSelectedEmployee.Tables(0).Rows.Count - 1
                    lstSelected.Items(i).Text = dsSelectedEmployee.Tables(0).Rows(i)(0) & " " & dsSelectedEmployee.Tables(0).Rows(i)(1)
                Next
            Else
                Me.lstSelected.Items.Clear()
            End If

        Catch ex As Exception
            Response.Write(ex.Message)
        End Try

出处：https://www.cnblogs.com/wequst/p/4009644.html

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