Compilare: main.cpp: In function 'int main()': main.cpp:32:56: 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 (e[i] >= '0' && e[i] <= '9' && i < e.size()) | ~~^~~~~~~~~~ main.cpp:50:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 50 | while (i < e.size()) | ~~^~~~~~~~~~ main.cpp:57:56: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 57 | while (e[i] >= '0' && e[i] <= '9' && i < e.size()) | ~~^~~~~~~~~~