Get All Url From String

How can I get all url from string and put them in array ?

For Ex :
$s="click here http://domain.com or here http://anydo.net";

I want to put all url in array
$Url[0]="http://domain.com";
$Url[1]="http://anydo.net";

My approach would be to split the string:
$words = split(' ',$line)
Then for each "word" found i'd try to match it:
ereg("^{http.*",$word)}

hope this help...