Compilare: user.cpp: In function ‘void mat2mul(int (*)[2], int (*)[2], int (*)[2])’: user.cpp:17:24: warning: argument to ‘sizeof’ in ‘void* memset(void*, int, size_t)’ call is the same expression as the destination; did you mean to dereference it? [-Wsizeof-pointer-memaccess] memset (res, 0, sizeof(res)); ^ user.cpp: In function ‘void identity2(int (*)[2])’: user.cpp:26:23: warning: argument to ‘sizeof’ in ‘void* memset(void*, int, size_t)’ call is the same expression as the destination; did you mean to dereference it? [-Wsizeof-pointer-memaccess] memset(res, 0, sizeof(res)); ^ user.cpp: In function ‘void copy2(int (*)[2], int (*)[2])’: user.cpp:32:25: warning: argument to ‘sizeof’ in ‘void* memcpy(void*, const void*, size_t)’ call is the same pointer type ‘int (*)[2]’ as the destination; expected ‘int [2]’ or an explicit length [-Wsizeof-pointer-memaccess] memcpy(res, src, sizeof(src)); ^