Compilare: main.cpp: In function 'bool operator==(const num&, const num&)': main.cpp:123:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 123 | while (i < a.val.length()) { | ~~^~~~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator+(const num&) const': main.cpp:161:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 161 | while (i < n.val.length()) { | ~~^~~~~~~~~~~~~~~~ main.cpp:168:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 168 | while (i < val.length()) { | ~~^~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator-(const num&) const': main.cpp:200:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 200 | while (i < aux.val.length() && i < n.val.length()) { | ~~^~~~~~~~~~~~~~~~~~ main.cpp:200:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 200 | while (i < aux.val.length() && i < n.val.length()) { | ~~^~~~~~~~~~~~~~~~ main.cpp:215:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 215 | if (j + 1 == aux.val.length() && aux.val[j] == '0') | ~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp:221:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 221 | while (i < aux.val.length()) | ~~^~~~~~~~~~~~~~~~~~ main.cpp: In member function 'num num::operator*(const num&) const': main.cpp:237:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 237 | for (int i = 0; i < val.length(); i++) | ~~^~~~~~~~~~~~~~ main.cpp:238:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 238 | for (int j = 0; j < n.val.length(); j++) | ~~^~~~~~~~~~~~~~~~ main.cpp:243:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 243 | for (int i = 0; i < a.size(); i++) { | ~~^~~~~~~~~~