Compilare: user.cpp: In function ‘void get_answers()’: user.cpp:62:15: warning: unused variable ‘l’ [-Wunused-variable] int i,j,k,l; ^ user.cpp: In function ‘void read()’: user.cpp:16:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:19:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf",&A[i][j]); ^ user.cpp: In function ‘int main()’: user.cpp:86:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.in","r",stdin); ^ user.cpp:87:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.out","w",stdout); ^