1 reply to this topic

[alok541]

class xyz
{

};
void main()
{
cout<<sizeof(xyz);
getch();
}


output=1 but why?
:love:

[ZekeDragon]

When you instantiate an object, it requires an address. The only way that it can be given an address is if there is SOME amount of memory it requires when it is instantiated, therefore, all class objects have to have a size in bytes of at least 1.

Imagine this situation:

xyz *o = new xyz();

If xyz is size 0, what exactly is new supposed to ask the OS for? If a request is made for 0 bytes, it is ignored, and what's worse there's no address to assign to the pointer *o, which will inevitably lead to undefined behavior when the user tries to use an object that couldn't possibly exist. Thus, your object must have at least ONE byte to assign an address in memory to, so pointers to it don't become wild or NULL for no good reason.