title: Checking if an 8 bit character is alphanumeric
body: <p>This C# code would return an unexpected result:</p>
  <pre class="lang-cs prettyprint-override"><code>char x = Convert.ToChar(0xff);
  Console.WriteLine( Char.IsLetterOrDigit(x));
  </code></pre>
  <p>It prints <code>True</code> were I was hoping for a <code>False</code>. I assume this is because <code>IsLetterOrDigit</code> is expecting a Unicode character as input versus the extended ascii value I convert from.</p>
  <p>How could I make this work? I am reading a continuous binary string from a serial port where problematic characters needs to be removed for reporting.</p>