title: What is the opposite of explode function?
body: <p>This is how I explode a sentence into an array of words:</p>
  
  <p><code>$words = explode(" ", $sentence)</code>;</p>
  
  <p>How do you do the opposite? (take an array such as <code>$words</code> with single numeric keys into a variable storing a string such as <code>$sentence</code> with spaces between words)</p>