C++: What is the size of an object of an empty class?
- by Ashwin
I was wondering what could be the size of an object of an empty class. It surely could not be 0 bytes since it should be possible to reference and point to it like any other object. But, how big is such an object?
I used this small program:
#include <iostream>
using namespace std;
class Empty {};
int main()
{
Empty e;
cerr << sizeof(e) << endl;
return 0;
}
The output I got on both Visual C++ and Cygwin-g++ compilers was 1 byte! This was a little surprising to me since I was expecting it to be of the size of the machine word (32 bits or 4 bytes).
Can anyone explain why the size of 1 byte? Why not 4 bytes? Is this dependent on compiler or the machine too? Also, can someone give a more cogent reason for why an empty class object will not be of size 0 bytes?
