Funktionales C++: accumulate

int add (int x, int y) {  return x + y; }

int s = 0;
return accumulate (l.begin(), l.end(), s, add);

Implementierung (in <numeric>)

template<typename _InputIterator, typename _Tp, 
         typename _BinaryOperation>
  _Tp  accumulate(_InputIterator __first, 
         _InputIterator __last, 
         _Tp __init, _BinaryOperation __binary_op)
    {
      for ( ; __first != __last; ++__first)
        __init = __binary_op(__init, *__first);
      return __init;
    }