title: A little confused on this recursion example
body: <pre><code>int gcd (int a, int b)
  {
     if (b == 0)
        return a;
     if (a == 0)
        return b;
     return gcd (b, a % b);
  }
  </code></pre>
  
  <p>What is the result of gcd (5, 15)?</p>
  
  <p>I ended up getting 15 but I'm not sure if it's correct, all the loops are confusing me.</p>