ASP.Net/Language Basics/Variable Scope

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block-level variables (C#)

<%@ Page Language="c#" %>
<script runat="server">
void Page_Load()
{
  if(1==1)
  {
      string strBlockLevelVariable;
      strBlockLevelVariable = "Very Short Lived!";
  
      lblMessage.Text = strBlockLevelVariable;
  }

}
</script>
<html>
<head>
<title>Creating Variables Example</title>
</head>
<body>
    <asp:Label runat="server" ID="lblMessage"/><br/>
</body>
</html>



Define page level variables (VB.net)

<%@ Page Language="VB" %>
<script runat="server">
    Dim myFirstNumber, mySecondNumber As Integer
    
    Sub SetVarsToInitialValues()
      myFirstNumber = 7
      mySecondNumber = 8
    
      Label1.Text = myFirstNumber
      Label2.Text = mySecondNumber
    End Sub
    
    Sub Button1_Click(sender As Object, e As EventArgs)
      SetVarsToInitialValues()
      Label3.Text = myFirstNumber + mySecondNumber
    End Sub
    
    Sub Button2_Click(sender As Object, e As EventArgs)
      SetVarsToInitialValues()
      Label3.Text = myFirstNumber - mySecondNumber
    End Sub
</script>
<html>
<head>
</head>
<body>
    <form runat="server">
        <p>
            <asp:Label id="Label1" runat="server">Label</asp:Label>
            &nbsp;+ 
            <asp:Label id="Label2" runat="server">Label</asp:Label>
            &nbsp;= 
            <asp:Label id="Label3" runat="server">Label</asp:Label>
        </p>
        <p>
            <asp:Button id="Button1" onclick="Button1_Click" runat="server" Text="Add"></asp:Button>
            <asp:Button id="Button2" onclick="Button2_Click" runat="server" Text="Subtract"></asp:Button>
        </p>
    </form>
</body>
</html>



Function Level variables (C#)

<%@ Page Language="C#" Debug="true" %>
<script runat="server">
    void Page_Load()
    {
      string strMyFuncVariable = "Function-Level Variable";
      if(Page.IsPostBack)
      {
          string strMyBlockVariableUsedInside = "Block Variable Used In Block";
          lblMessageBlockInBlock.Text = strMyBlockVariableUsedInside;
          lblMessageFunction.Text = strMyFuncVariable;
      }
    
    }
</script>
<html>
<head>
    <title>Variable Scope</title>
</head>
<body>
    <form runat="server">
        <asp:Label id="lblMessageBlockInBlock" runat="server" text="DEFAULT - BlockInBlock"></asp:Label>
        <br />
        <asp:Label id="lblMessageFunction" runat="server" text="DEFAULT - Function"></asp:Label>
        <br />
        <asp:Button id="Button1" runat="server" Text="Submit"></asp:Button>
    </form>
</body>
</html>



Local variable inside a function (VB.net)

<script language="vb" runat="server"> 
Sub Page_Load()  
    Response.Write ("<BR />Calling Subroutine 1...")
    Call Subroutine_1()
    Response.Write ("<BR />Calling Subroutine 2...")
    Call Subroutine_2()
    Response.Write ("<BR />Calling Subroutine 1...")
    Call Subroutine_1()
End Sub
  Sub Subroutine_1()
    Dim Different As String
    Different = "<i>Hello I"m the variable Different in Subroutine 1</i>"
    Response.Write (Different)
  End Sub
  Sub Subroutine_2()
    Dim Different As String
    Different = "<b>Hello I"m the variable Different in Subroutine 2</b>"
    Response.Write (Different)
  End Sub
</script>
<html>
<head>
<title>Scope</title>
</head>
<body>
</body>
</html>



Page level variable and function level variable (VB.net)

<script language="vb" runat="server"> 
    Dim Global As String ="<br><u>Hello I"m a persistent global variable</u>"   
Sub Page_Load()  
    Response.Write (Global)     
    Response.Write ("<BR />Calling Subroutine 1...")
    Call Subroutine_1()
    Response.Write ("<BR />Calling Subroutine 2...")
    Call Subroutine_2()
    Response.Write ("<BR />Calling Subroutine 1...")
    Call Subroutine_1()
End Sub
  Sub Subroutine_1()
    Dim Different As String
    Different = "<i>Hello I"m the variable Different in Subroutine 1</i>"
    Response.Write (Different)
    Response.Write (Global)
  End Sub
  Sub Subroutine_2()
    Dim Different As String
    Different = "<b>Hello I"m the variable Different in Subroutine 2</b>"
    Response.Write (Different)
    Response.Write (Global)
  End Sub
</script>
<html>
<head>
<title>Scope</title>
</head>
<body>
</body>
</html>



Page Level Variable (C#)

<%@ Page Language="C#" Debug="true" %>
<script runat="server">
         string strVariableGlobal = "Variable Global: Use me anyplace on the page";
    
         void Page_Load()
         {
            string strMyVariable1 = "Block Variable Used In Block";
    
            if (1==1)
            {
              string strMyVariable2 = "Block Variable Used In Block";
              string strMyVariable3 = "Block Variable Used After Block";
              lblMessageBlockInBlock.Text = strVariableGlobal;
    
            }
    
            lblMessageProcedure.Text = strVariableGlobal;
            SubProcedure2();
         }  
    
        void SubProcedure2()
        {
            lblMessageBlockOutBlock.Text = strVariableGlobal;
        }
</script>
<html>
<head>
    <title>Variable Scope</title>
</head>
<body>
    <form runat="server">
        <asp:Label id="lblMessageBlockInBlock" runat="server" text="DEFAULT - BlockInBlock"/>
        <br />
        <asp:Label id="lblMessageBlockOutBlock" runat="server" text="DEFAULT - BlockOutBlock"></asp:Label>
        <br />
        <asp:Label id="lblMessageProcedure" runat="server" text="DEFAULT - Procedure"></asp:Label>
        <br />
    </form>
</body>
</html>
Источник — «http://nfex.ru/index.php?title=ASP.Net/Language_Basics/Variable_Scope&oldid=2198»