converting from mat file struct to c++ pack4 struct

Hi I have *.mat file holding mat struct and c++ struct with the same fields but pack 4

reading from mat field by field, filling the c++ struct as pointer array this is for not need to know the field names exactly in the process

in my code I read field from mat , EX float --> insert it to struct pointer with offset, ex st[0]=field

field from mat, EX char --> insert it to struct pointer with offset, ex st[4]=field

etc..

the problem is keeping the pack_4 rule in the struct, is there better way? is there a code doing it already?

thanks