Hello.. Im working on my c++ application, and I have string (user input) where I would have to replace some variables/substrings in it.. For example lets say user give input: string str "this is test $some_variable some more text $random(1-5) $random(1-9)"; My program has a vector <string> of variables that program should look for, for this case lets say "some_variable" and "random". Now I want to replace $some_variable and both $random 'variables' with another string, and I want $some_variable to be replaced with some other string, and $random to be replaced with random number generated in range from 1-5 and 1-9, for instance $random(1-5) = "3", $random(1-9) = "6". So I would get "this is test some string some more text 3 6"; This would be an easy thing to do, if I wouldnt have $random variable which makes different string each time you call it, so I'm in concern what would be a right/best approach to this.. I was thinking of using boost::regex and search with boost::regex expression("[%$](some_variable|random|some_more_variables)(<([^>]+)>)?"); until I come to the string end.. Thanks a lot for help Kind regards Aljaz