title: How to check if "set" in c
body: <p>If I allocate a C array like this:</p>
  
  <pre><code>int array[ 5 ];
  </code></pre>
  
  <p>Then, set only one object:</p>
  
  <pre><code>array[ 0 ] = 7;
  </code></pre>
  
  <p>How can I check whether all the other keys ( <code>array[1]</code>, <code>array[2]</code>, …) are storing a value?  (In this case, of course, they aren't.)</p>
  
  <p>Is there a function like PHP's <code>isset()</code>?</p>
  
  <pre><code>if ( isset(array[ 1 ]) ) ...
  </code></pre>