Compilare: main.cpp: In function 'long long int factor()': main.cpp:22:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 22 | while (idx < s.size() && s[idx] >= '0' && s[idx] <= '9') /// s[idx] - cifra | ~~~~^~~~~~~~~~ main.cpp: In function 'long long int termen()': main.cpp:34:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | while (idx < s.size() && (s[idx] == '*' || s[idx] == '/')) | ~~~~^~~~~~~~~~ main.cpp: In function 'long long int eval()': main.cpp:53:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 53 | while (idx < s.size() && (s[idx] == '+' || s[idx] == '-')) | ~~~~^~~~~~~~~~