Compilare: main.cpp: In member function 'int Evaluator::getSum()': main.cpp:18:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | while(index < expression.size() && (expression[index] == '+' || expression[index] == '-')) { | ~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'int Evaluator::getProduct()': main.cpp:32:21: 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(index < expression.size() && (expression[index] == '*' || expression[index] == '/')) { | ~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'int Evaluator::getNumber()': main.cpp:58:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 58 | while(index < expression.size() && '0' <= expression[index] && expression[index] <= '9') { | ~~~~~~^~~~~~~~~~~~~~~~~~~