[Year 12 SofDev] Records and Arrays

Fri Aug 20 07:26:18 EST 2010

Love the definition Adrian, and although we can find exceptions to it pretty
well covers what I think VCAA want as a definition and is simple enough for
students. I would just be careful with the line where you say that records
are similar to arrays, because when we implement them in languages that
support them, we use arrays of records and this could cause confusion in the
students minds (or arrays as part of the definition of a record). While we
still have arrays and records, we need to stick as close to their intended
purpose and I think that the record was intended as a way to combine
different data types.

Cheers Don

From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Janson, Adrian A
Sent: Thursday, 19 August 2010 8:54 PM
To: Year 12 Software Development Teachers' Mailing List
Subject: Re: [Year 12 SofDev] Records and Arrays

Hi everyone,

I know that some of you were happy with the definitions I posted before, and
I do want to keep them simple - but, how about this:

One-Dimensional Arrays

A one dimensional (or 1D) array is a data structure in which variables are
grouped together under the same name and accessed via a number known as the
'index'.  Although an array typically contains only one data type, it can
consist of multiple data types (as is possible in some languages such as PHP
and Python).

....

Records

A record is a structure that can be used to group together variables for a
particular purpose.  Records are similar to arrays but whereas an array
usually contains elements all of the same type, the variables within a
record are usually of different types and sizes.  Indexing the elements of a
record is often done via an identifier which is declared at the same time as
the record.

The important thing - as some have stated already, is for us to be able to
tell students: 'this is the standard definition of an array and a record'.
So if a student were asked on the exam 'what is an array', they could answer
'an array is a data structure in which variables are grouped together under
the same name and accessing using an index number'. - and get full marks.

Adrian

Adrian Janson B.Sc, Dip.Ed, M.Ed
Director of ICT
Melbourne High School, Forrest Hill, South Yarra, Victoria 3141 Australia.
Phone: 03 9826 0711 International: +61 3 9826 0711
Fax: 03 9826 8767 International: +61 3 9826 8767
E-mail: janson.adrian.a at edumail.vic.gov.au
<https://www.edumail.vic.gov.au/mail/janson.adrian.a/Drafts/RE:%20%5bYear%20
12%20SofDev%5d%20Records%20and%20Arrays.EML/janson.adrian.a at edumail.vic.gov.
au> 

Website: http://www.mhs.vic.edu.au <http://www.mhs.vic.edu.au/> 

Blog: http://jansona.edublogs.org <http://jansona.edublogs.org/> 

  _____  

From: sofdev-bounces at edulists.com.au on behalf of David Dawson
Sent: Thu 19/08/2010 8:46 PM
To: sofdev at edulists.com.au
Subject: Re: [Year 12 SofDev] Records and Arrays

What a fascinating discussion this is! (No I mean it!)
When I started teaching Pascal in 1998 - I was so confused by "records"
- and came to see them as "customised data types" and - having just
learnt some Java and C++ - I figured they were really like Classes - or
even objects.
In any case I have not come up against this mysterious "data structure"
in the other languages I have explored - in C they are constructed and
can be called anything - and I bet that the library file could be
renamed ""list_o_stuff" - even in Pascal.
I prefer PHP at present and in PHP - like so many languages - the thing
people seem to miss is that in "weakly typed languages" everything just
starts as a String and is dealt with "contextually" as someone cleverly
pointed out earlier. If there are numbers we wish to multiply the
language figures this out by our operations - very smooth!
An array is a list defined by a computer language to store temporary
Strings! Some languages limit these - if they insist on strong variable
typing.
I really hope records are just amended out of any reference in the study
design.
IMHO they died 10 years ago!

David Dawson
Head of Information Technology Learning Area
Head of Learning Technologies
St Kilda Rd Campus
Wesley College
577 St Kilda Rd
Melbourne 3004
Ph 8102 6340
Mob 0425 718147

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