title: Pass string if the parameter value is null
body: <p>I need to pass multiple parameters in a function. My requirement is the parameter value should not be NULL. If
  the parameter is NULL pass "TBD" instead. </p>
  
  <p>e.g. </p>
  
  <pre><code>getBookInfo (string bookId, string bookName, string bookAuthor) 
  //if any of the parameters is NULL, pass "TBD" string in parameter
  </code></pre>
  
  <p>How can I do this? Can I do this using ternary operator, and if so, how? </p>