title: convert ipv4 netmask to cidr format
body: <p>I have the ip and netmask </p>
  
  <pre><code>192.168.1.0 255.255.255.0
  </code></pre>
  
  <p>I need to convert the netmask into cidr format</p>
  
  <pre><code>192.168.1.0/24
  </code></pre>
  
  <p>How do I convert ipv4 address and netmask into cidr format?</p>
  
  <p>I am using PHP5.6</p>