(C++) Answer of exercise #9: No for-loops #18

 

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

 

 

 

 

 

Question

 

Replace the for-loop. You will need:

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

 

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

 

 

 

 

 

Answer

 

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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; } #include <vector> #include <functional> int SumPositives(const std::vector<int>& v) {   return ::accumulate_if(v.begin(),v.end(),0,std::bind2nd(std::greater<int>(),0)); }