(C++) SumPositives

 

Math code snippet to sum all positive elements in a container.

 

There are multiple ways to implement SumPositives:

1. Using an algorithm (preferred [1][2])
2. Using a for-loop

 

 

 

 

 

SumPositives using an algorithm

 

---

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

 

 

 

 

 

SumPositives using a for-loop

 

---

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)); }

 

 

 

 

 

References

 

1. Bjarne Stroustrup. The C++ Programming Language (3rd edition). ISBN: 0-201-88954-4. Chapter 18.12.1 : 'Prefer algorithms over loops'
2. Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Chapter 84: 'Prefer algorithm calls to handwritten loops.'