Compilare: user.cpp: In member function ‘POLYNOMIAL POLYNOMIAL::operator+(POLYNOMIAL&)’: user.cpp:31:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<result.size(); ++i) ^ user.cpp:34:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i >= this->size()) ^ user.cpp:37:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i >= w.size()) ^ user.cpp: In member function ‘POLYNOMIAL POLYNOMIAL::operator-(POLYNOMIAL&)’: user.cpp:50:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<result.size(); ++i) ^ user.cpp:53:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i >= this->size()) ^ user.cpp:56:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i >= w.size()) ^ user.cpp: In function ‘int main()’: user.cpp:133:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x >= v1.size()) ^ user.cpp:143:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x >= v2.size()) ^ user.cpp:152:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=v2.size(); i <v1.size(); ++i) ^ user.cpp:157:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<v.size(); ++i) ^