String literals in C++ have type const char and are not allowed to be changed even if the implementation will not place them in a read-only memory.
Instead of pointers to string literals you can use character arrays. For example
char anna = "Anna";
char maria ="Maria";
But take into account if you want to append array maria to array anna then array anna shall have enough memory (size) to accept maria. As the size of maria is equal to 6 then anna shall have size equal to at least 10. So the definition of anna shall be