title: isset() and PHP global variables
body: <p>Regarding global variable initialization,</p>
  
  <pre><code>function hello_testing() {
      global $conditional_random;
      if (isset($conditional_random)) {
          echo "foo is inside";
      }
  }
  </code></pre>
  
  <p>The global variable (conditional_random) may not be initialized before the <code>hello_testing()</code> function is called.</p>
  
  <p>So, what happens to my validation via <code>isset()</code> when <code>$conditional_random</code> is not initialized? Will it fail or it will always be true?</p>