c++ - Erasing a container element using iterators -

my current homework assignment has me creating iterator class list. i'm stuck @ creating erase(iterator where) function.

current code (reduced fit question):

class list {     class _iter     {         friend class list;     public:         _iter(listelem *pcurr, list *plist);          /* *, ->, ++, --, == , != operators overloaded */      private:         listelem *pcurr_; list *plist_;     };      typedef _iter iterator;      iterator erase(iterator where); }; 

with erase being implemented so:

// precondition: list has been checked size > 0. list::iterator list::erase(list::iterator& where) {     // erasing element in list.     if(where == end() && == begin())     {         pop_back(); // or pop_front();         return iterator(0, this);     }      // elem @ end     if(where == end())     {         pop_back();         return end();     }     else      {         // elem @ beginning         if(where == begin())         {             pop_front();             return ++begin();         }     }      // elem somewhere between beginning , end.     iterator temp(where);     // node next pcurr_ should point 1 before pcurr_     where.pcurr_->next->prev = where.pcurr_->prev;     // node before pcurr_ should point 1 after pcurr_     where.pcurr_->prev->next = where.pcurr_->next;     // return node after pcurr_     ++temp;     delete where.pcurr_;     --size_;     return temp; }  

the first 3 cases- element, element @ end , element @ beginning- okay. coded fine , need absolutely no knowledge , private access _iters members. however, if element not in positions, have (seemingly) no choice violate encapsulation , change pcurr_ (element of list) directly.

is there way avoid this? looked inside stl list, used other functions _next_node_(/* stuff */) , _prev_node_(/* stuff */) weren't useful me. google searches give me helpful results on how use erase function, not how write myself.

question: there way in can erase element pointed iterator without having grab it's pcurr_ member?

1. do not use identifiers beginning underscore followed uppercase letter. reserved standard library , system writers. although writing own list class, not writing standard library.

2. end() 1 element past end of list, not last element. (to actual last iterator of list can l.rbegin().base() happens).

3. pass iterator value, not non-const reference.

4. why concerned modifying pcurr?