Compilare: main.cpp: In function 'int main()': main.cpp:36:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 36 | for(int i = 0; i < a.size(); ++i) | ~~^~~~~~~~~~ main.cpp:75:21: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 75 | while(i < a.size() && a[i] >= '0' && a[i] <= '9') | ~~^~~~~~~~~~ main.cpp: In function 'long long int eval(long long int, long long int, char)': main.cpp:20:1: warning: control reaches end of non-void function [-Wreturn-type] 20 | } | ^