Compilare: main.cpp: In function 'long long int numar(std::__cxx11::string&)': main.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < expresie.size() && '0' <= expresie[i] && expresie[i] <= '9'; i++) ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'long long int termen()': main.cpp:39:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (poz < expresie.size() && expresie[poz] != '+') ~~~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'long long int calcul()': main.cpp:70:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (poz < expresie.size()) ~~~~^~~~~~~~~~~~~~~~~