1.5 STL

• A Good reference book is "effective STL".
• Effective STL item 48. Always include the proper headers.
  1. Include corresponding header when you use container.
  2. All but four algorithms are declared in <algorithm>. inner_product, adjacent_differene, partial_sum and accumulate are in the <numeric>.
  3. Special kinds of iterators , including istream_iterators are in the <iterator>
  4. Standard functors, eg less<T> and functor adapter not1, bind2nd are declared in <functional>. They are not recommended to use in C++11. Because C++ 11 introduce function and bind template.
• STL is a good example of generic programming, there is specific book about topic of generic programming, if you have time in the future, you can look at it.
• Containers, iterators, functions objects, and algorithms four parts. Use functor customize algorithms, then apply algorithm on Containers by iterators. Such as algorithm find, you can input two Iterators into the it. Find don’t care what container which he will look for a value in it. Find() in fact is a template function, it doesn’t use inheritance to make generic programming, but use template. All the idea is explained here: http://www.cplusplus.com/reference/algorithm/for_each/
  struct Sum{ 
      Sum(): sum{0} { } 
      void operator()(int n) { sum += n; } 
      int sum; 
  }; 
  ////////////////////// 
   std::vector<int> nums{3, 4, 2, 8, 15, 267}; 
   
   std::for_each(nums.begin(), nums.end(), [](int &n){ n++; }); 
   // g++ -std=c++11 compile lambda syntax. 
   
   Sum s = std::for_each(nums.begin(), nums.end(), Sum()); 
   // It return a Sum struct. 
   cout<<s.sum<<endl;