title: Shift left/right adding zeroes/ones and dropping first bits
body: <p>I've got to program a function that receives </p>
  
  <ul>
  <li>a binary number like <code>10001</code>, and</li>
  <li>a decimal number that indicates how many shifts I should perform.</li>
  </ul>
  
  <p>The problem is that if I use the C++ operator <code>&lt;&lt;</code>, the zeroes are pushed from behind but the first numbers aren't dropped... For example</p>
  
  <blockquote>
    <p>shifLeftAddingZeroes(10001,1)</p>
  </blockquote>
  
  <p>returns <code>100010</code> instead of <code>00010</code> that is what I want.</p>
  
  <p>I hope I've made myself clear =P</p>