var_dump(preg_grep('@^HTTP(.*?)\w{2,}$@i', $array)); //finds a string starting with http (regardless of case) (matches two)
var_dump(preg_grep('@(/\w+\.*/*)+@', $array)); //finds / followed by one or more of a-z, A-Z and 0-9, followed by zero or more . followed by zero or more / all more than once. (matches all)
var_dump(preg_grep('@^http://[^w]{3}.*$@i', $array)); //finds http:// (at the beginning of a string) not followed by 3 characters that aren't w's then anything to the end of the sttring (matches one)
var_dump(preg_grep('@.*?\.co\.uk$@i', $array)); //finds any address ending in .co.uk (matches none)
var_dump(preg_grep('@^HTTP(.*?)\w{2,}$@i', $array, PREG_GREP_INVERT)); //same as first example but the array created contains everything that is NOT matched but the regex (matches three)