title: Bit mask in C
body: <p>What is the best way to construct a bit mask in C with <code>m</code> set bits preceded by <code>k</code> unset bits, and followed by <code>n</code> unset bits:</p>
  
  <pre><code>00..0 11..1 00..0
    k     m     n
  </code></pre>
  
  <p>For example, k=1, m=4, n=3 would result in the bit mask:</p>
  
  <pre><code>01111000
  </code></pre>