PHP Code to find the common alphabets in AMITABH BACHCHAN and RAJNIKANTH

common-aplhabets.php

<?php
   echo "<h1>PHP Code to find the common alphabets in AMITABH BACHCHAN and RAJNIKANTH</h1>";
   $string1 = "AMITABH BACHCHAN";
   $string2 = "RAJNIKANTH";
   $a1 = strlen($string1);
   $a2 = strlen($string2);
   echo "common alphabets in AMITABH BACHCHAN AND RAJNIKANTH are :\n";
   for($i = 0;$i<$a1;$i++)
    {
      for($j=0;$j<$a2;$j++)
      {
        if($string1[$i]==$string2[$j])
          echo $string1[$i];
      }
    }
?>