Check if a string starts with a specific character

Use a php function preg_match to see if a string starts with a particular character, for
example:

<?php

        if (preg_match('/^a/', $str)) {

                echo "String starts with an a";

        }

?>

To do a case insensitive search use an 'i' flag:

<?php

        if (preg_match('/^a/i', $str)) {

                echo "String starts with an a or A";

        }

?>