On Jan 19, 2013 3:00 AM, "horseriver" wrote: > > On Fri, Jan 18, 2013 at 03:27:25PM +0000, Jonathan Wakely wrote: > > >> printf("size of A is %d \n",sizeof(A)); > > >> //printf("size of B is %d \n",sizeof(B)); > > > > Careful, you are using %d which expects an int but sizeof gives a size_t > Thanks! > I have not understand what you mean ? size_t is a unsigned int ,I think it does not matter here It's quite easy to understand. Your printf should be passed an int The sizeof operator does not give you an int. On my platform it gives a 64-bit integer. Even on your platform it does not give you an int, unsigned int is not int. The code is not portable, so you should be careful about writing and using such code. If you compile with warnings you will get a warning about it. It's your code so you can choose to ignore it if you think you know better than the compiler. But you should be careful.