Compilare: main.cpp: In function 'void count_letters(ecuatie&)': main.cpp:19:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 19 | for(int i = 0; i < e.s.size(); i++){ | ~~^~~~~~~~~~~~ main.cpp: In function 'bool factor(ecuatie&)': main.cpp:52:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 52 | if(e.poz < e.s.size() && e.s[e.poz] == '('){ | ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'bool expresie_and(ecuatie&)': main.cpp:71:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 71 | while(e.poz < e.s.size() && e.s[e.poz] == '&'){ | ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'bool expresie_or(ecuatie&)': main.cpp:82:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 82 | while(e.poz < e.s.size() && e.s[e.poz] == '|'){ | ~~~~~~^~~~~~~~~~~~