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2013-04-01T03:23:31.060
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There already is <a href="http://en.cppreference.com/w/cpp/iterator/iterator_traits" rel="nofollow">std::iterator_traits</a> in the standard library in <code><iterator></code>. Your <code>using namespace std;</code> makes the one in the header visible along with your user defined one. Remove <code>using namespace std;</code> from the code. The other big problem is places like here: <code>reference operator*()</code>. With templates, when you use <code>reference</code> the compiler only looks inside of <code>Checked_iter</code> to see if it exists. You need to fully qualify it like this: <code>typename iterator_traits<Iter>::reference operator*()</code> or use what is called the injected class name, i.e. <code>typename Checked_iter::reference operator*()</code>. Otherwise, the compiler will tell you that it does not exist. BTW, <code>reference</code>, etc. is what is known a a dependent name. Once the above errors are fixed, you will need to include <code><stdexcept></code> to get <code>std::out_of_range</code>, etc. And prepend everything with <code>std::</code>. Also, in <code>difference_type index() {return curr-c.begin();}</code>, <code>c</code> is a pointer, so you need to change to <code>c->begin()</code>. Lots of errors... I got a <a href="http://liveworkspace.org/code/4xvsYI%2437" rel="nofollow">compilable program</a>: <pre><code>#include <iostream> #include <vector> #include <iterator> #include <exception> #include <cstddef> #include <stdexcept> template<class Iter> struct iterator_traits{ typedef typename Iter::iterator_category iterator_category; typedef typename Iter::value_type value_type; typedef typename Iter::difference_type difference_type; typedef typename Iter::pointer pointer; typedef typename Iter::reference reference; }; // specialization for pointer //template<class T> struct iterator_traits<T*> //{ // typedef ptrdiff_t difference_type; // typedef T value_type; // typedef T* pointer; // typedef T& reference; // typedef random_access_iterator_tag iterator_category; //}; template<class Cat, class T, class Dist=ptrdiff_t, class Ptr=T*, class Ref=T&> struct iterator { typedef Cat iterator_category; typedef T value_type; typedef Dist difference_type; typedef Ptr pointer; typedef Ref reference; }; template<class Ran> typename iterator_traits<Ran>::difference_type dist_helper(Ran first, Ran last, std::random_access_iterator_tag) { return last-first; //rely on random access } template<class In > typename iterator_traits<In>::difference_type distance(In first, In last) { return dist_helper(first, last, iterator_traits<In>::iterator_category()); } //Code template <class Cont, class Iter=typename Cont::iterator> class Checked_iter : public iterator_traits<Iter>{ //deriving from iterator_traits Iter curr; Cont* c; //.... public: void valid(Iter p) { if ( c->end() == p) return; for(Iter pp= c->begin(); pp != c->end(); ++pp){ if (pp==p) return; } throw std::out_of_range("out of range"); } friend bool operator==(const Checked_iter& i, const Checked_iter& j) { return i.c == j.c && i.curr == j.curr; } //no default initialzer //use defaul t copy constructor and cop assignment. Checked_iter(Cont& x, Iter p):c(&x), curr(p) {valid(p);} typename iterator_traits<Iter>::reference operator*() { if (curr == c->end()) throw std::out_of_range("out of range"); return *curr; } typename iterator_traits<Iter>::pointer operator->() { return &*curr; // checked by * } Checked_iter operator+(typename iterator_traits<Iter>::difference_type d ) // for random access iterators only { if(c->end() - curr <= d ) throw std::out_of_range("out of range"); return Checked_iter(c ,curr+d ); } typename iterator_traits<Iter>::reference operator[](typename iterator_traits<Iter>::difference_type d ) // for random access iterators only { if (c->end() - curr <= d) throw std::out_of_range("out of range"); return c[d]; } Checked_iter& operator++() // prefix ++ { if (curr == c->end()) throw std::out_of_range("out of range"); ++curr; return *this ; } Checked_iter& operator++(int) { Checked_iter tmp= *this; ++*this; //Checked by prefix ++ return tmp; } Checked_iter& operator--() //prefix-- { if(curr == c->begin()) throw std::out_of_range("out of range"); --curr; return *this; } Checked_iter& operator--(int) //postfix { Checked_iter tmp=*this; --*this; //checked by prefix -- return tmp; } typename iterator_traits<Iter>::difference_type index() {return curr - c->begin();} //random access only Iter unchecked() {return curr;} //+-< }; template<class Cont, class Iter> Checked_iter<Cont,Iter>make_checked(Cont& c, Iter i) { return Checked_iter<Cont, Iter>(c,i); } template<class Cont>Checked_iter<Cont,typename Cont::iterator>make_checked(Cont& c) { return Checked_iter<Cont, typename Cont::iterator>(c,c.begin()); } void f_count(std::vector<int>& vec) { int count=0; try{ Checked_iter<std::vector<int>> p(vec, vec.begin()); while(true){ ++p; ++count; } } catch(std::out_of_range){ std::cout<<"overrun after"<<count<<"tries\n"; } } void print_v(std::vector<int>vec) { for(auto i=vec.begin();i != vec.end(); ++i) std::cout<<*i<<" "; } void test_f(){ int a[] = {0,1,2,3,4,5,6,7,8,9}; std::vector<int> l(a, a+sizeof(a)/sizeof(int)); print_v(l); f_count(l); } int main() { test_f(); return 0; } </code></pre>
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