Concatenating variable into a regex php -

i have these arrays (array , array2)

$urls = array("http://piggington.com/pb_cash_flow_positive") 

i have regular expression

(preg_match("/\/{2}.*?\./", $array[$i], $matches)) 

it checks comes after 2nd slash , before 1st dot. find

/piggington. 

now want concatenate variable inside following regular expression, search specific string.

i tried:

$matches_imploded = implode($matches); $matches_imploded = preg_quote($matches_imploded, '/'); $match_with_other_array = preg_grep("/\/{2}".$matches_imploded."\./", $array2); 

but it's not finding matches.. doing wrong? should looking inside array2 , making positive match $matches_imploded

between second slash , first dot found $matches_imploded 

to match comes after // , before first dot, need use \k or positive lookbehind.

preg_match("~/{2}\k[^.]*(?=.)~", $array[$i], $matches) $matches_imploded = implode($matches); $matches_imploded = preg_quote($matches_imploded, '/'); $match_with_other_array = preg_grep("/\/{2}".$matches_imploded."\./", $array2);