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
>> }
>>
>> 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)
