i have few strings, if string below
$string ="w?w+f=w?wefwef?blahblah"; $desiredstring ="w?w+f=w&wefwef?blahblah"; if format, trying replace second ? & else nothing.
i've tried regex , preg_match no luck.
in current case solution is:
$string ="w?w+f=w?wefwef?blahblah"; $desiredstring = preg_replace('/^(.+?\?.+?)\?/', '$1&', $string); echo $desiredstring; output:
w?w+f=w&wefwef?blahblah n-th occurence regexp:
/^((?:(?:.*?\?){0}.*?))\?/ // first occurence /^((?:(?:.*?\?){1}.*?))\?/ // second occurence /^((?:(?:.*?\?){2}.*?))\?/ // third occurence // etc. 