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Option Strict On disallows operands of type Object for operator '<>'. Use the 'Is' operator to test for object identity.

Posted on 2006-10-28
Medium Priority
Last Modified: 2013-11-19
<%@ Page Language="VB" Explicit="True" Strict-"True" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SqlClient" %>
<script runat="server">
      Public Sub btnLogin_Click(sender As Object, e As EventArgs)
            If Not Page.IsPostBack Then
                  Exit Sub
            End If
          Dim con As SqlConnection
          Dim cmd As SqlCommand
          Dim rdr As SqlDataReader
          Dim str As String
        Dim booOk As Boolean = False

          con = New SqlConnection("Data Source=;User ID=fffff;Password=fffff;Initial Catalog=ccccc")
            str = "Select * FROM tblUsers WHERE username = '" & txtUsername.Value & "' "
            cmd = New SqlCommand(str, con)
              rdr = cmd.ExecuteReader
                        If Not rdr.Read Then
                        lblErrMsg.Text = "Enter a valid User ID!"
                    ElseIf rdr.Item("Password") <> txtPassword.Value Then
                        lblErrMsg.Text = "Password is incorrect!"
                             booOk = True
                    End If                 


        If booOk Then
            FormsAuthentication.RedirectFromLoginPage(txtUsername.Value ,False)
        End If
    End Sub

    <link rel="stylesheet" type="text/css" href="KB/inc/Format.css">
      <title>IT Knowledge Base</title>
    <form method="post" runat="server">
        <h1 align="center">
              IT Knowledge Base
            <table class="normalbold" width="350" border="0" cellspacing="0" cellpadding="10" align="center" bgcolor="#cccccc">
                <tr align="left">
                    <td valign="top">
                    <td valign="top">
                          <input type="text" id="txtUsername" runat="server"></input>
                <tr align="left">
                    <td valign="top">
                    <td valign="top">
                          <input type="text" id="txtPassword" runat="server"></input>
                    <td colspan="3" align="center">
                        <asp:Label ID="lblErrMsg" Runat="Server" CssClass="err" Visible="True"/>
                        <input type="submit" id="btnLogin" value="Login" OnServerClick="btnLogin_Click" runat="server"></input>


When I run the webpage I get the following error:

BC32013: Option Strict On disallows operands of type Object for operator '<>'. Use the 'Is' operator to test for object identity.

It is referring to the statement that has 'ElseIf rdr.Item("Password") <> txtPassword.Value Then'


So I looked up the IsNot command and replaced the <> with it and got this error:

Option Strict On disallows implicit conversions from 'System.Object' to 'Boolean'.


What is my best bet to do?  rdr.Item and txtPassword will return a string and not a boolean wouldnt it?  But the result of the comparison would return a boolean?  Please help.  Thanks.

Question by:molard
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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 17825849
what about this:

 ElseIf NOT( rdr.Item("Password") = txtPassword.Value) Then

Author Comment

ID: 17825885
Thanks for the quick reply!

It gives me the following error:

Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: BC32013: Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity.

Source Error:


Line 25:                         If Not rdr.Read Then
Line 26:                         lblErrMsg.Text = "Enter a valid User ID!"
Line 27:                     ElseIf NOT rdr.Item("Password") = txtPassword.Value) Then
Line 28:                         lblErrMsg.Text = "Password is incorrect!"
Line 29:                     Else

I know that I can turn Option Strict off and it will work fine.  I wanted to get it working with Option Strict since I already have my other pages working fine with it.


I tried to take the advice it gave me and replace the = with Is.  It wouldnt let me log in and told me the Password is incorrect which references to those same lines of code.  Do you know anything else I might could try?  Thanks again!

Author Comment

ID: 17825892
I tried it exactly the way you posted which was:

ElseIf NOT( rdr.Item("Password") = txtPassword.Value) Then

and I also took out the ( ) on the outside and tried it.  It gave me the same error.
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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 17825903

ElseIf NOT( rdr.Item("Password").Value = txtPassword.Value) Then
LVL 143

Accepted Solution

Guy Hengel [angelIII / a3] earned 200 total points
ID: 17825905
resp use the toString():

ElseIf NOT( rdr.Item("Password").toString() = txtPassword.Value.toString()) Then

Author Comment

ID: 17825920
The statement:

ElseIf NOT( rdr.Item("Password").toString() = txtPassword.Value.toString()) Then

worked great!  Thanks for your help!

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