Compilare: main.cpp: In function 'bool is_in_string(std::string&, int&)': main.cpp:29:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | return position < str.size(); | ~~~~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:42:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | while (position < expression.size()) { | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~