Compilare: main.cpp: In function 'std::__cxx11::string conj(std::__cxx11::string)': main.cpp:20:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < s.size() ; i++ ) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:59:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < s.size() ; i++ ) { ~~^~~~~~~~~~