reference type methods

[Ruben]

Why would a method that is defined to return a reference such as with the
operator overload of [], operator[],

href& operator[](int index){
return _array[index];
}

not cause a type mismatch compiler error?

Ruben

--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium

[Ian Collins]

Ruben wrote:

Why would a method that is defined to return a reference such as with the
operator overload of [], operator[],

href& operator[](int index){
return _array[index];
}

not cause a type mismatch compiler error?

Why should it? Assuming _array is an array of href, it just returns a
reference to an href.

--
Ian Collins.

[Ruben]

On Mon, 14 Jul 2008 22:11:19 +1200, Ian Collins wrote:

Ruben wrote:

>Why would a method that is defined to return a reference such as with
the operator overload of [], operator[],

href& operator[](int index){
return _array[index];
}
}
not cause a type mismatch compiler error?

Why should it? Assuming _array is an array of href, it just returns a
reference to an href.

hmmm

the symbol array would not be a reference
it would be defined

private:
int _array[default_size];

This comes up from a text book, and I found it puzzling.

Ruben
--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium

[Ian Collins]

Ruben wrote:

On Mon, 14 Jul 2008 22:11:19 +1200, Ian Collins wrote:

>Ruben wrote:

>>Why would a method that is defined to return a reference such as with
the operator overload of [], operator[],

href& operator[](int index){
return _array[index];
}
}
not cause a type mismatch compiler error?

Why should it? Assuming _array is an array of href, it just returns a
reference to an href.

hmmm

the symbol array would not be a reference
it would be defined

private:
int _array[default_size];

Yes, but _array[index] in an int. I can only guess that href is a
typedef alias for int. The function returns a reference to that int.

--
Ian Collins.

[Ruben]

On Mon, 14 Jul 2008 22:30:24 +1200, Ian Collins wrote:

Ruben wrote:

>On Mon, 14 Jul 2008 22:11:19 +1200, Ian Collins wrote:

>>Ruben wrote:
Why would a method that is defined to return a reference such as with
the operator overload of [], operator[],

href& operator[](int index){
return _array[index];
}
}
not cause a type mismatch compiler error?

Why should it? Assuming _array is an array of href, it just returns a
reference to an href.

hmmm

the symbol array would not be a reference it would be defined

private:
int _array[default_size];

Yes, but _array[index] in an int. I can only guess that href is a typedef
alias for int. The function returns a reference to that int.

Ah - your right. I made a mistake and it confused you. I'm so sorry

int& operator[](int index){
return _array[index];
}
But I still am not sure why it doesn't cause a type mismatch error.

Ruben

--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium

[Ian Collins]

Ruben wrote:

On Mon, 14 Jul 2008 22:30:24 +1200, Ian Collins wrote:

>Yes, but _array[index] in an int. I can only guess that href is a typedef
alias for int. The function returns a reference to that int.

Ah - your right. I made a mistake and it confused you. I'm so sorry

int& operator[](int index){
return _array[index];
}

But I still am not sure why it doesn't cause a type mismatch error.

Because there isn't one.

The type of _array[index] is int. The function returns a reference to
an int, so there isn't any mismatch.

--
Ian Collins.

[Ruben]

On Mon, 14 Jul 2008 23:26:07 +1200, Ian Collins wrote:

>}
But I still am not sure why it doesn't cause a type mismatch error.

Because there isn't one.

The type of _array[index] is int. The function returns a reference to an
int, so there isn't any mismatch.

Thanks

That is the part I don't satisfactorly understand. Why is it not
returning the rvalue of the array element.

Why is it different than this

int x, y[10] = {1,2,3,4,5,6,7, 8,9,10};

x = y[3];

I would think the requested return value doen't match the method
definition and I'd have to return something like this

return &i[index];

Ruben

--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium

[Ian Collins]

Ruben wrote:

On Mon, 14 Jul 2008 23:26:07 +1200, Ian Collins wrote:

>>}
But I still am not sure why it doesn't cause a type mismatch error.

Because there isn't one.

The type of _array[index] is int. The function returns a reference to an
int, so there isn't any mismatch.

Thanks

That is the part I don't satisfactorly understand. Why is it not
returning the rvalue of the array element.

That would be const reference.

Why is it different than this

int x, y[10] = {1,2,3,4,5,6,7, 8,9,10};

x = y[3];

How is it different? It is more like

int& x = y[3];

I would think the requested return value doen't match the method
definition and I'd have to return something like this

return &i[index];

No, you are out by one level of indirection. &i[index] takes the
address of i[index] and yields a pointer to int.

It looks like you should do some background reading on references and
pointers, particularly their differences.

--
Ian Collins.

[Ruben]

On Mon, 14 Jul 2008 23:36:45 +1200, Ian Collins wrote:

How is it different? It is more like

int& x = y[3];

>I would think the requested return value doen't match the method
definition and I'd have to return something like this

return &i[index];

No, you are out by one level of indirection. &i[index] takes the address
of i[index] and yields a pointer to int.

It looks like you should do some background reading on references and
pointers, particularly their differences.

agreed. I understand pointers. I've never seen references at all until
C++ and the texts aren't defining them well.

One thing I know is that is an element of an int array is accessed through
either indirection

*(p +4);

or though the array

a[10];

I get a return value of an integer.

But it seems that if I use a reference on the left of the assignment

int& i = a[];
int b[10];

i = b[6];

I seem to get an entirely different behavior.
Ruben

--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium

[Ruben]

On Mon, 14 Jul 2008 23:36:45 +1200, Ian Collins wrote:

Ruben wrote:

>On Mon, 14 Jul 2008 23:26:07 +1200, Ian Collins wrote:

>>>But I still am not sure why it doesn't cause a type mismatch error.

Because there isn't one.

The type of _array[index] is int. The function returns a reference to
an int, so there isn't any mismatch.

Thanks

That is the part I don't satisfactorly understand. Why is it not
returning the rvalue of the array element.

That would be const reference.

>Why is it different than this

int x, y[10] = {1,2,3,4,5,6,7, 8,9,10};

x = y[3];

How is it different? It is more like

int& x = y[3];

>I would think the requested return value doen't match the method
definition and I'd have to return something like this

return &i[index];

No, you are out by one level of indirection. &i[index] takes the address
of i[index] and yields a pointer to int.

Yes but i[index] returns a literal integer. In fact, I don't know of any
way of returning a varriable, only the data that a symbolic variable
refers to.

I do know how to return an address of a variables assigned space, though a
pointer, like in scanf for example.

return i[index] isn't an lvalue. Yet when the fuction is defined as
returning a reference, it seems to have a seperate syntax unrelated to
the rest of a references implimentation. The only way I know of returning
an actually reference...act ually I don't know a way because even under
this circumstance

int =y =3, z;
int & x = y;

z = x; //STILL an RVALUE assigned and copied to z

so

return x;//should still be an rvalue returned (unless you return a point)

This seems to be a seperate property of references.

Ruben

>
It looks like you should do some background reading on references and
pointers, particularly their differences.

--
http://www.mrbrklyn.com - Interesting Stuff
http://www.nylxs.com - Leadership Development in Free Software

So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998

http://fairuse.nylxs.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002

"Yeah - I write Free Software...so SUE ME"

"The tremendous problem we face is that we are becoming sharecroppers to our own cultural heritage -- we need the ability to participate in our own society."

"I'm an engineer. I choose the best tool for the job, politics be damned.<
You must be a stupid engineer then, because politcs and technology have been attached at the hip since the 1st dynasty in Ancient Egypt. I guess you missed that one."

© Copyright for the Digital Millennium