title: How to store a digit string into an arbitrary large integer?
body: <p>Let <code>ib</code> be the input base and <code>ob</code> the output base. <code>str</code> is the ASCII representation of some arbitrary large integer <code>x</code>. I need to define <code>f</code> such as:</p>
  
  <pre><code>f(str="1234567890", ib=10, ob=16) = {4, 9, 9, 6, 0, 2, 13, 2}
  </code></pre>
  
  <p>... where the return type of <code>f</code> is an <code>int</code> array containing the base <code>ob</code> digits of this integer. We assume that <code>2 &gt;= ob &lt;= MAX_INT</code> and <code>2 &gt;= ib &lt;= 10</code>, and <code>str</code> will always be a valid string (no negative needed).</p>