14. Using const iterator

• begin( ) and end( ) provide special iterators for a vector:

  
      using std::vector;
      vector< int > v1;
      //...
      int total = 0;
  
      vector< int >::const_iterator iter = v1.begin();
  
      while ( iter != v1.end() ) {
          total += *iter;
          ++iter;
      }