void some_func(char* ch);
some_func(*cha); // equivalent to some_func(cha);
edit, NB: string in C++ means std::string, you're talking about C strings here. Unless this is an assignment or you have some very specific need (ie, to actually treat some data as an array of characters rather than as a contiguous string) you probably don't want to use C strings.
Moreover, you should realize that you can't convert char*  to char* at all because they're not at all the same: the former is an array of the latter. You can either select one of the C strings with bracket notation or dereference it to get the first one, per above.