reallocation

Printable View

03-04-2008
George2

reallocation

Hello everyone,

We alway meet with the term reallocation, but after some deep thinking, I am confused what exact definition of what means reallocation. Here is some statements from the book The C++ Standard Library as quoted below.

My two questions,

1. How do you understand the term reallocation in the book quoted section?

2. Are there any standard definition for reallocation?

My understanding, reallocation means making storage larger or smaller (or making the same size, but different address? not sure?), whether or not it involves free existing memory (e.g. vector) or not (e.g. deque) depends on internal implementation. It is hard to find a suitable definition for reallocation, if you have, please share with me. :-)

section 6.3.1 Abilities of deques

--------------------
Deques provide no support to control the capacity and the moment of reallocation. In particular, any insertion or deletion of elements other than at the beginning or end invalidates all pointers, references, and iterators that refer to elements of the deque. However, reallocation may perform better than for vectors, because according to their typical internal structure, deques don't have to copy all elements on reallocation.
--------------------

thanks in advance,
George
03-05-2008
CornedBee

I disagree with this definition. In my opinion, a deque simply doesn't perform reallocation, only allocation and deallocation.

There's no standard, though.
03-05-2008
George2

Thanks CornedBee,

How do you understand the reallocation term if you do not agree with me in the quoted statement?

section 6.3.1 Abilities of deques

--------------------
Deques provide no support to control the capacity and the moment of reallocation. In particular, any insertion or deletion of elements other than at the beginning or end invalidates all pointers, references, and iterators that refer to elements of the deque. However, reallocation may perform better than for vectors, because according to their typical internal structure, deques don't have to copy all elements on reallocation.
--------------------

Quote:

Originally Posted by CornedBee

I disagree with this definition. In my opinion, a deque simply doesn't perform reallocation, only allocation and deallocation.

There's no standard, though.

regards,
George
03-05-2008
CornedBee

Can you explain to me just why you repeat the quote?

Anyway, I gave my definition of reallocation in another thread.
03-05-2008
George2

Thanks CornedBee,

After reading your another thread, I understand your points. Your points are, you do not agree with the author of the book to use term reallocation, since in your points, there is no cencept and operation of reallocation for deque. Right?

Quote:

Originally Posted by CornedBee

Can you explain to me just why you repeat the quote?

Anyway, I gave my definition of reallocation in another thread.

regards,
George
03-05-2008
CornedBee

Correct.
03-05-2008
George2

Thanks CornedBee,

Question answered.

Quote:

Originally Posted by CornedBee

Correct.

regards,
George
03-05-2008
Daved

Insertion in the middle of a deque causes elements to be moved, which invalidates iterators, references, etc. Apparently Stroustrup (edit: I mean Josuttis) is referring to this as reallocation.
03-05-2008
CornedBee

The book in question is Josuttis's, I think.
03-06-2008
George2

Hi Daved,

If you have found a formal definition for what is a reallocation in STL, please feel free to share with us, and I think it will definitely bring benefit to us.

Quote:

Originally Posted by Daved

Insertion in the middle of a deque causes elements to be moved, which invalidates iterators, references, etc. Apparently Stroustrup (edit: I mean Josuttis) is referring to this as reallocation.

Quote:

Originally Posted by CornedBee

The book in question is Josuttis's, I think.

Yes, CornedBee, I am talking about this book,

--------------------
C++ Standard Library, The: A Tutorial and Reference

Nicolai M. Josuttis
Publisher: Addison Wesley
First Edition August 06, 1999
ISBN: 0-201-37926-0, 832 pages
--------------------

regards,
George
03-06-2008
Daved

>> If you have found a formal definition for what is a reallocation in STL.

I have not. I doubt that such a formal definition exists. I don't think it matters that much, as usually we can determine the meaning by the context of the statement.
03-06-2008
George2

Thanks Daved,

I also do not find it out from wikipedia.

Quote:

Originally Posted by Daved

>> If you have found a formal definition for what is a reallocation in STL.

I have not. I doubt that such a formal definition exists. I don't think it matters that much, as usually we can determine the meaning by the context of the statement.

regards,
George