PHP：str_replace不适用于某些字符

Question

I have the following code to replace certain characters:

<?php
function xmlEscape($string)
{
    return str_replace(array('&', '<', '>', '\'', '"'), array('&amp;', '&lt;', '&gt;', '&apos;', '&quot;'), $string);
}
$xxx = 'The character & is ampersand and < stands for "less than". ';

echo xmlEscape($xxx)." <p/>";
echo str_replace ('&', '&amp;', $xxx."<p/>");
echo str_replace ( 'character','letter', $xxx);
?>

The result is :

The character & is ampersand and < stands for "less than".
The character & is ampersand and < stands for "less than".
The letter & is ampersand and < stands for "less than".

Only the third works fine. What could be the cause ? I once used that code in other scripts and that function worked. What makes a function works in one script and does not work in others ? Using Firefox as browser.

Thanks.

Answer 1

if you trying like this

echo str_replace ('&', 'amp', $xxx."<p/>");

then it is working fine.

"&" is unicode character and it is rendering on browser if you want to see the changes check it on firebug.

Answer 2

I've tried your code and it works properly. If you see your browser source code, you will see

The character &amp; is ampersand and &lt; stands for "less than".  <p>
The character &amp; is ampersand and &lt; stands for "less than". </p>
<p>The letter &amp; is ampersand and &lt; stands for "less than".

Answer 3

Sorry... Looks like it is replaced! But the browser interprets the escape character and displays it again as "&".