C#

static int Main(string[] args)
{
  // Don't use magic or made-up numbers. Winerror.h defines common
  // errors for Win32 already.
  if (args.Length != 1) return ERROR_INVALID_PARAMETER;
}
const int ERROR_INVALID_PARAMETER = 87;

double diff = (double)1/3  - (double).33333;
if(Math.Abs(diff) < Double.Epsilon)
    Console.WriteLine("They are equal.");
else
    Console.WriteLine("They are not equal.");

IDisposable o = new C();
try
{
  C s = o as C; //this is not allowable for structs, 
  // lets assume it would then it would go out of scope before Dispose can be called
  // your code here
}
finally
{
  o.Dispose();
}

error CS0077: The as operator must be used with a reference type ('sharptest.C' is a value type)

using (C s = new C())
{
  Console.WriteLine(s.clan.ToString());
}