using System;

public class Example

{

   public static void Main()

   {

      string[] values = { null, String.Empty, "True", "False", 

                          "true", "false", "    true    ", "0", 

                          "1", "-1", "string" };

      foreach (var value in values) {

         bool flag;

         if (Boolean.TryParse(value, out flag))

            Console.WriteLine("'{0}' --> {1}", value, flag);

         else

             Console.WriteLine("Unable to parse '{0}'. The flag is now {1}", 

                              value == null ? "<null>" : value, flag);

      }                                     

   }

}

// The example displays the following output:

//       Unable to parse '<null>'.

//       Unable to parse ''.

//       'True' --> True

//       'False' --> False

//       'true' --> True

//       'false' --> False

//       '    true    ' --> True

//       Unable to parse '0'.

//       Unable to parse '1'.

//       Unable to parse '-1'.

//       Unable to parse 'string'.