Compilare: main.cpp: In function 'long long int eval(std::string, int, int)': main.cpp:24:44: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 24 | while (s[i] >= '0' && s[i] <= '9' && i < s.size()){ | ~~^~~~~~~~~~ main.cpp:29:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | if (i < s.size()) | ~~^~~~~~~~~~ main.cpp:32:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 32 | while (i < s.size()) | ~~^~~~~~~~~~ main.cpp:36:52: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 36 | while (s[i] >= '0' && s[i] <= '9' && i < s.size()){ | ~~^~~~~~~~~~