Compilare: user.cpp: In function ‘void get_primes(std::vector<int>&, int)’: user.cpp:16:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 4; i < v.size(); i += 2) { ^ user.cpp:19:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 3; i < v.size(); i += 2) { ^ user.cpp:22:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i * 2; j < v.size(); j += i) { ^ user.cpp: In function ‘int main()’: user.cpp:44:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned int ii = 0; primes[ii] * primes[ii] <= b; ++ii) { ^ user.cpp:53:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= (b - a) / 32 + 1; ++i) { ^