[Boost-users] hi i am a beginner user, there are some problem when using the library, can anyone help me with that ? plz

i am trying to use the boost polygon function for example boost::geometry::read_wkt("multipolygon(((0 0 , 3 0 , 3 2 , 0 2)))", q); however i want to use the changing input such as "multipolygon(((A B, 0 2, 0 0, 4 0, 4 0)))" and A, B are the parameters defined by my previous array, but it ends up with showing the bad lexical cast since the parameters A and B can not be used or read if there is any solution that i can use the changing parameters as my polygon input, i kept searching for the answer but still can not find it can anyone plz help me, and i will be so grateful with that. thanks again!