Needing help changing content of a variable

I have an rss pulling script that I need help with. For the summary, i need to change all the apostrophes that are pulled ( ' ) into ( \' )

$summary = $item['summary'];	
$summary = substr($summary,0,240)."...";
line that changes all ' to \'

Code (markup):

 

$summary = "That's your's don't y'know?";
$summary = preg_replace("/\'/", "\\\'", $summary);
echo $summary;

PHP:

This will produce:
That\'s your\'s don\'t y\'know?

 

Worked. Thanks.