Compilare: user.cpp: In function ‘matrice sum(const matrice&, const matrice&)’: user.cpp:81:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A.size(); ++i) ^ user.cpp:82:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < A.size(); ++j) ^ user.cpp: In function ‘matrice prod(const matrice&, const matrice&)’: user.cpp:96:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A.size(); ++i) ^ user.cpp:97:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < A.size(); ++j) ^ user.cpp:98:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < A.size(); ++k) ^