Compilare: user.cpp: In function ‘void make_system()’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int do_gauss()’: user.cpp:52: warning: no return statement in function returning non-void user.cpp: In function ‘int solve_system()’: user.cpp:63: warning: no return statement in function returning non-void user.cpp: In function ‘int main()’: user.cpp:67: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:68: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result