Compilare: user.cpp: In function ‘int swap(int&, int&)’: user.cpp:17:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int rotate_matrix()’: user.cpp:213:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:217:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("treid.in" ,"r", stdin ); ^ user.cpp:218:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("treid.out","w", stdout); ^ user.cpp:220:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &N, &M); ^ user.cpp:223:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &matrix[i][j]); ^