(C++) Answer of exercise #9: No for-loops #19

 

This is the answer of Exercise #9: No for-loops.

 

 

 

 

 

Question

 

Replace the for-loop. You will need:

• std::bind2nd.htm
• std::greater.htm
• std::multiplies.htm
• A conditional std::accumulate

 

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int ProductNonZeroPositives(const std::vector<int>& v) {   const size_t sz = v.size();   int product = 0;   for (size_t i=0; i!=sz; ++i)   {     if (v[i]>0) product*=v[i];   }   return product; }

 

 

 

 

 

Answer

 

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//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; } #include <vector> //From http://www.richelbilderbeek.nl/CppProductNonZeroPositives.htm int ProductNonZeroPositives(const std::vector<int>& v) {   return ::std::accumulate_if(     v.begin(),     v.end(),     1,     std::multiplies<int>(),     std::bind2nd(std::greater<int>(),0)); }