title: How can I check if a char is a letter or a number?
body: <p>I have a string and I want to loop it so that I can check if every char is a letter or number.</p>
  
  <pre><code>$s = "rfewr545 345b";
  
  for ($i=1; $i&lt;=strlen($s); $i++){
     if ($a[$i-1] == is a letter){
        echo $a[$i-1]." is a letter";
     } else {
        echo $a[$i-1]." is a number";
     }
  }
  </code></pre>
  
  <p>How can I check if a char is a letter or a number?</p>