C#

private void getAllFiles(string sExt, string sFolder)
{
    DirectoryInfo di = new DirectoryInfo(sFolder);
    FileInfo[] fi = di.GetFiles(sExt, SearchOption.AllDirectories);
    //List<FileInfo> fi = new List<FileInfo>(di.EnumerateFiles(sExt, SearchOption.AllDirectories));
    foreach (FileInfo file in fi)
    {
        AddNewFile(Path.Combine(di.ToString(), file.ToString()));
        counter++;
    }
    lblTotalFiles.Text = counter.ToString();
    //SetText(counter.ToString());
}

public enum Type
    {
        None = 0,
        Found =1,
        NotAval = 2
        
    };

public enum ShortType
    {
        None = 0,
        Fd =1,
        NA = 2
    };


class Properties
{
public Type type;
};

 List<Properties> props;
//After that List is populated
...
...
//Now I want to type cast the Type enum in the entire list to ShortType with out looping through the entire list 
//Please advice 

<connectionStrings>
    <add name="SqlServerConnectionString" connectionString="server=NAPALDEVDBS02.dev.psisystems.local\DEV08; database=VPO1; User ID={0}; Password={1}; Pooling=True; Min Pool Size=5; Max Pool Size=40; Connect Timeout=10;" providerName="System.Data.SqlClient" />
    <add name="SqlServerConnectionPropertiesString" connectionString="Initial Catalog=VPO1;Integrated Security=False;Uid=WSAccountData;Pwd=drUc5u8r;" providerName="System.Data.SqlClient" />
    <add name="VPO1" connectionString="server=NAPALDEVDBS02.dev.psisystems.local\DEV08; database=VPO1; User ID=VPOServer; Password=Mon186ster;" />
  </connectionStrings>

ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();

fileMap.ExeConfigFilename = @"c:\test1\app.config";
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);

var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");

ExeConfigurationFileMap fileMapWeb = new ExeConfigurationFileMap();
fileMapWeb.ExeConfigFilename = @"C:\test2\web.config";
Configuration configWeb = ConfigurationManager.OpenMappedExeConfiguration(fileMapWeb, ConfigurationUserLevel.None);

var connectionStringsWeb = (ConnectionStringsSection)configWeb.GetSection("connectionStrings");

//here I got connectionString element in connectionStringsWeb from web.config file. But how to append this connectionString element to app.config file.