title: What is argument evaluation?
body: <p>Herbert Schildt says:</p>
  
  <blockquote>
    <p>In some situations, real function should be used in place of function-like-macro, for example: where code size is to be minimized or where an argument must not be evaluated more than once.</p>
  </blockquote>
  
  <p>What does he mean by <em>"an argument must not be evaluated more than once?"</em></p>