title: C# ConfigurationManager Problem
body: <p>I have upgrade the project from framework3.5 to framework4.0.Right Now i am using Visual studio 2010.Here is my app.config file</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
   &lt;configuration&gt;
   &lt;appSettings&gt;
  &lt;add key="DBConnectionString" value="User ID=sa;Password=password123;Initial   Catalog=DishTV_Voting;Persist Security Info=True;Data Source=ENMEDIA-50CB48D"/&gt;
   &lt;/appSettings&gt;
    &lt;/configuration&gt;
  </code></pre>
  
  <p>Here when i am working with framework 3.5 I used the config file as</p>
  
  <pre><code>  using  System.Configuration;
  namespace Voting_Editor_Tool_New
  {
  public partial class Voting_Editor_Tool : Form
  {
      SqlConnection myConnection;
  
      string connectString = ConfigurationSettings.AppSettings["DBConnectionString"];
    public void getdata()
    {
  
  
  
     myConnection = new SqlConnection(connectString); 
       ....
     } 
   }
  }
  </code></pre>
  
  <p>When I upgrade to framework 4.0 the line </p>
  
  <pre><code>   ConfigurationSettings.AppSettings["DBConnectionString"];
  </code></pre>
  
  <p>shows a warning message as </p>
  
  <p>'System.Configuration.ConfigurationSettings.AppSettings' is obsolete: 'This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings'.</p>
  
  <p>I tried with ConfigurationManager.AppSettings["DBConnectionString"]; but it shows a error
  as</p>
  
  <pre><code>The name 'ConfigurationManager' does not exist in the current context
  </code></pre>
  
  <p>Can anyone just how to solve the problem.Thanks in advance.</p>