(C++) accumulate_if

Algorithm similar to std::accumulate, except that accumulate_if also needs a predicate argument.


//From http://www.richelbilderbeek.nl/CppAccumulate_if.htm

template

  <

  typename InputIterator,

  typename ElementType,

  typename Predicate

  >

const ElementType accumulate_if(

  InputIterator first,

  const InputIterator last,

  ElementType init,

  const Predicate predicate)

{

  for (; first != last; ++first)

    if (predicate(*first)) init += *first;

  return init;

}


//From http://www.richelbilderbeek.nl/CppAccumulate_if.htm

template

  <

  typename InputIterator,

  typename ElementType,

  typename BinaryOperation,

  typename Predicate

  >

const ElementType std::accumulate_if(

  InputIterator first,

  const InputIterator last,

  ElementType init,

  const BinaryOperation binary_op,

  const Predicate predicate)

{

  for (; first != last; ++first)

    if (predicate(*first)) init = binary_op(init, *first);

  return init;

}

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