htmlentities not working

Am I correct in thinking the following code should output what& #039 ;s up (*)

$foo = "what's up";
$foo = htmlspecialchars($foo, ENT_QUOTES);
print $foo;

When I check the page source I see what's up not what& #039 ;s up (*)

The same thing happens with htmlentities.

It translates &, < and > but doesn't seem to be picking up on the ENT_QUOTES

Have I misunderstood these functions or is there something wrong?

Many thanks.

because you're using htmlspecialchars, not htmlentities

$foo = "what's up";
$foo2 = htmlentities($foo);
echo $foo2;

As I mentioned, I tried with both htmlentities and htmlspecialchars.

Any ideas why ENT_QUOTES makes no difference in my scripts?

Many thanks.

No clue. I just tried it with htmlentities, and it worked fine for me...