How to print string in reverse order without using strrev() function

How to print string in reverse order without using strrev() function:

<?php

$str_name = 'siva';
$len = strlen($str_name);

for($i=($len-1); $i>=0;$i--)
{
echo $str_name[$i];
}

?>



Another one

<?php

$str = 'siva';
$strrvse = implode(array_reverse(str_split($str)));

echo $strrvse;

?>