On Fri, Jan 18, 2013 at 01:46:22PM +0000, 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));
> > }
> >
> > 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.
thanks!
Here I do not define a object of type A ,just do sizeof operation to a A struct ,not a specified object.
So if I defined A a , does sizeof(a) have the same mean with sizeof(A) ?
what does the sizeof operator essentially?
>
> Andrew.
>
>
