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Re: why is this result ?
On Fri, Jan 18, 2013 at 03:27:25PM +0000, Jonathan Wakely wrote:
> On 18 January 2013 13:46, Andrew Haley wrote:
> > On 01/18/2013 03:50 AM, horseriver wrote:
> >> hi:
> >> I am doing a test for c++;
> >>
> >> here is my code:
> >>
> >> #include <stdio.h>
> >> class A
> >> {};
> >>
> >> class B
> >> {
> >> public:
> >> B(){};
> >> ~B(){};
> >> };
> >>
> >> int main()
> >> {
> >>
> >> 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
>
> >> }
> >>
> >> output is "size of A is 1 " ,I can not understand this result ,
> >> there is no data in class A ,why here its size is 1?
> >
> > Because it's not possible to have an object with nonzero size. The
> > address of every object must be unique, so they have to be separated by
> > one byte anyway.
>
> Just to be clear, this is required by the standard (and the platform ABI)