Compilare: main.cpp: In function 'void eval()': main.cpp:17:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | while(i < T.size()) | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:112:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 112 | for(int i = 0; i < T.size(); i++) | ~~^~~~~~~~~~