sukhvir

• Sep 26th, 2007

 

Size of empty structure in C++ is 1 byte, because compiler assign 1 byte for structure name.

mucdull

 Profile Answers by mucdull 

• Nov 16th, 2008

 

Because the class has no members (especially no virtual functions) its objects naturally should have 0 bytes. However the objects must be legally creatable because the class is not abstract (having no pure virtual functions) so there must be a way to address the objects. You cannot address something that does not take up any memory. Since the smallest addressable space is 1 byte, the compiler allocates 1 byte for the objects so to make them addressable.

To dwell on the topic, what do you think is the size of objects of this class?

class C { virtual void Go() {} };

santhosh.kanchanapally

 Profile Answers by santhosh.kanchanapally Questions by santhosh.kanchanapally

• Feb 18th, 2009

 

struct Emp
{
};

int _tmain(int argc, _TCHAR* argv[])
{
    cout<<"The size of structure is :"<<sizeof(Emp);
    getchar();
    return 0;
}

output::
The size of structure is : 1

santhosh.kanchanapally

 Profile Answers by santhosh.kanchanapally Questions by santhosh.kanchanapally

• Feb 18th, 2009

 

Hence the size of an empty structure is 1 byte

dkuy1

 Profile Answers by dkuy1 

• Aug 8th, 2009

 

The Standard C++ language definition says:
A class with an empty sequence of members and base class objects is an empty
class. Complete objects and member sub-objects of an empty class type shall have
nonzero size.
Most compiler give a size of 1.

cantrip . org/emptyopt . html This link explains in great detail why this is
and when it can have a different size if use as part of a class or struct: