title: How to have a default "NULL" value for an unsigned integer (ex: NaN to floating points)?
body: <p>I am trying to write some code that will accept either one or two 16-bit hex value from the user and store it in some register. Now these values are stored in a <code>uint16_t</code> array of size 2.</p>
  
  <p>This array is then passed to the function that will pass these values one bit at a time. My problem is, if the user only inputs one 16-bit value, then I want to only write that one word, but if the user types two values, then both should be passed to the register.</p>
  
  <p>As of now, I have the check for one or two words, simply being if the second 16-bit value in the array is ==0x0000, then the user only wrote one value.</p>
  
  <p><strong>How can I check to see if there is only one value, without using the value of the number as its test case?</strong></p>
  
  <p>For example: floating-point values have NaN, so I could use isnan() instead of checking to see if the value was 0x0000.</p>