title: How can I check a variable if contains numbers 0 to 9 and characters a to z?
body: <p>I would like to know how can I check if a variable contains numbers 0 to 9 and characters a to z, like that:</p>
  
  <pre><code> if($string contains numbers[0-9] and characters[a-z])
   {
    echo "true";
  } else {echo "false";}
  </code></pre>