Question

Which of the following functions will take a vector of strings and return a list of integers containing the sizes of the strings without using any loops or recursion?

For example, when provided a vector v0 with the strings ["abc", "", "defg", "h"], the function f(v0) should return a list of integers [3,0,4,1].

	A.	std::list<size_t> f(const std::vector<std::string>& v0) { std::list<size_t> result; for (std::vector<std::string>::iterator it = v0.begin(), it != v0.end(), it++) { result.push_back((*it).size()); } return result; }
	B.	std::list<size_t> f(const std::vector<std::string>& v0) { std::list<size_t> result; std::transform(v0.begin(), v0.end(), std::back_inserter(result), [&](const std::string& s) { result s.size(); }); return result; }
	C.	int* f(std::string[] v0) { int* result = new int[v0.length]; for (int i = 0; i < v0.length; i++) { result[i] = v0[i].size(); } return result; }
	D.	std::list<size_t> f(const std::vector<std::string>& v0) { std::list<size_t> result; std::for_each(v0.begin(), v0.end(), [](const std::string& s) { return s.size(); }); return result; }

Answer 1

Options A,C,D are using loops.

So, answer is Option B

std::list<size_t> f(const std::vector<std::string>& v0)  
{
   std::list<size_t> result;
   std::transform(v0.begin(), v0.end(), std::back_inserter(result), [&](const std::string& s) {
      result s.size();
   });
   return result;  
}  

Option B