Why reference variable inside class always taking 4 bytes irrespect of type? (on 32-bit system)

Question

Hi, I have below code, running on 32-bit windows, visual-studio.

template <class T>
class Test
{
public:
 T &ref;
 Test(T &x)
  :ref(x)
 {}
};

int main()
{
 cout<<"sizeof Test<int> : "<<sizeof(Test<int>)<<endl;
 cout<<"sizeof Test<double> : "<<sizeof(Test<double>)<<endl;
 cout<<"sizeof Test<char> : "<<sizeof(Test<char>)<<endl;
}

Output is:

sizeof Test<int> : 4
sizeof Test<double> : 4
sizeof Test<char> : 4

Compiler giving 4 bytes for reference variable inside class irrespect of the type of reference. Variable value can not be stored in those 4 bytes.

What information compiler will store in those 4 bytes ?

is it internally storing the address of referent? so that reference and referent both can write to the same location to be in sync with each other.

Or is it storing name of referent in symbol table ?

Answer 1

Those for bytes are the reference. A reference is just a pointer internally, and pointers typically use 4 bytes on a 32bit system, irrespective of the data types because it is just an address, not the value itself.

Answer 2

Why reference variable inside class always taking 4 bytes irrespect of type?

It isn't!

C++03 5.3.3

When applied to a reference or a reference type, the result is the size of the referenced type.

Also 8.3.2 says

It is unspecified whether or not a reference requires storage.