title: Generate combination array PHP
body: <p>Hi Guys i have an array like this</p>
  
  <pre><code>$array1 = array('a','b','c','d)
  </code></pre>
  
  <p>and i want to combine with output like this</p>
  
  <ul>
  <li>'a,b,c'</li>
  <li>'a,b,d'</li>
  <li>'a,c,d'</li>
  <li>'b,c,d'</li>
  </ul>
  
  <p>The problem is to create a function with a variable number and not multiple variable, can anybody help me?</p>