Compilare: main.cpp: In function 'bool operator==(const num&, const num&)': main.cpp:136:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 136 | while (i < a.val.length()) | ~~^~~~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator+(const num&) const': main.cpp:178:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 178 | while (i < n.val.length()) | ~~^~~~~~~~~~~~~~~~ main.cpp:186:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 186 | while (i < val.length()) | ~~^~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator-(const num&) const': main.cpp:220:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 220 | while (i < aux.val.length() && i < n.val.length()) | ~~^~~~~~~~~~~~~~~~~~ main.cpp:220:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 220 | while (i < aux.val.length() && i < n.val.length()) | ~~^~~~~~~~~~~~~~~~ main.cpp:237:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 237 | if (j + 1 == aux.val.length() && aux.val[j] == '0') | ~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp:243:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 243 | while (i < aux.val.length()) | ~~^~~~~~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator*(const num&) const': main.cpp:260:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 260 | for (int i = 0; i < val.length(); i++) | ~~^~~~~~~~~~~~~~ main.cpp:261:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 261 | for (int j = 0; j < n.val.length(); j++) | ~~^~~~~~~~~~~~~~~~ main.cpp:266:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 266 | for (int i = 0; i < a.size(); i++) | ~~^~~~~~~~~~