eval.in

<?php

function xml_entities($string) {
    return strtr(
        $string, 
        array(
            "<" => "&lt;",
            ">" => "&gt;",
            '"' => "&quot;",
            "'" => "&apos;",
            "&" => "&amp;",
        )
    );
}

$text = "Test &amp; <b> and encode </b> :)";
echo xml_entities($text);