c++ - range based loop C++11 for range(L,R) -

c++11 hasn't range-based-loop ranged integral sequence.

for(auto e : {0..10} )  // wouldn't compile!!! 

so decided simulate it.

template< class t , bool enable = std::is_integral<t>::value > struct range_impl {     struct iterator     {         constexpr t operator * ()const noexcept { return value; }         iterator& operator ++()noexcept { ++value; return *this; }          friend         constexpr bool operator != (const iterator & lhs, const iterator rhs ) noexcept         {             return lhs.value != rhs.value;         }         t value;     };      constexpr iterator begin()const noexcept { return { first }; }     constexpr iterator end  ()const noexcept { return { last  }; }       t first;     t last ; };      template< class t > range_impl<t>  range(t first , t last) noexcept {     return {first, last}; }  int main(){      // print numbers in [ 0..10 ), i.e. 0 1 2 3 4 5 6 7 8 9      for(auto e : range(0,10) ) std::cout << e <<  ' ';      std::cout << std::endl; } 

q: how generalize method forwarditerators?

example:

template< class forwarditerator, class t > bool find(forwarditerator first, forwarditerator last, t const& value) {      for(auto e: range(first, last) ) if (e == v) return true;      return false; } 

specialization

template< class iterator> struct range_impl<iterator, false> {     range_impl(iterator first, iterator last)     : first(first), last(last)     {}      constexpr iterator begin()const noexcept { return { first }; }     constexpr iterator end  ()const noexcept { return { last  }; }      iterator first;     iterator last ; }; 

test:

int main(){      for(auto e : range(0,10) ) std::cout << e <<  ' ';      std::cout << std::endl;      const char* a[] = { "say", "hello", "to", "the", "world" };      for(auto e : range(a, + 5) ) std::cout << e <<  ' ';      std::cout << std::endl; }