[Year 12 SofDev] Records and Arrays

Laurie Savage savage.john.l at edumail.vic.gov.au
Thu Aug 19 08:43:05 EST 2010


Hmm, messy but I don't see any other way. So we teach the kids that this is
a "fact" or definition which does not apply to half of the languages being
used. Maybe we should be teaching them to prepare COBOL programs on punched
cards too.

Laurie

-----Original Message-----
From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Guy Flaherty
Sent: Thursday, 19 August 2010 8:41 AM
To: 'Year 12 Software Development Teachers' Mailing List'
Subject: Re: [Year 12 SofDev] Records and Arrays

After a quick bit of research, the following approved languages do not
follow the 'definition' of an array as stated on page 161 of the Fitzpatrick
& Keane text:

Objective C
Python
Perl
Ruby
PHP
Visual Fox Pro

The other six language do. According to the definitions, the above languages
do not have an 'array' type but are indeed following the definition for a
'record'. Despite the fact that for each of these languages the structures
are described and explained as 'arrays' in their documentation and not
referred to as 'record' types.

It would seem that Adrian's point of these definitions being used in the
study design is important, and must be considered a requirement of the
course. Equally, if you teach one of the languages above, your students are
not going to understand this well without specific help, in my opinion, as
this will not be their experience in practice.

The simple answer is that any language type that allows for multiple items
to be referred to as part of a single variable, when the items are required
to be of the same type you have an 'array' and when the items are allowed to
be of differing types you have a 'record'. According to the study design but
purely language dependent in real life.

Guy Flaherty
Xavier College
 
>>> "Adrian Janson" <janson.adrian.a at edumail.vic.gov.au> 18/08/10 05:58 PM
>>> 
Hi Guy and all,

 

The definition of array and record are as you stated and I would have
thought that this was a common thing to all languages - but I am not
familiar with PHP at all - and was surprised to see that you could mix data
types in an array!  It is important to remember that it is in the study
design (and the next one to) and so is fair game for the examiners (even
though as you said - it would be possibly a controversial topic given the
way PHP treats arrays and records....)

 

Cheers,

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

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

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

 

-----Original Message-----
From: sofdev-bounces at edulists.com.au [mailto:sofdev-bounces at edulists.com.au]
On Behalf Of Guy Flaherty
Sent: Wednesday, 18 August 2010 2:58 PM
To: sofdev at edulists.com.au
Subject: Re: [Year 12 SofDev] Records and Arrays

 

Laurie,

 

I initially thought exactly as you stated when I looked at the reference in
the book. So I did a quick search and in languages like c and pascal arrays
must be of the same data type and records(pascal)/struct(c) can have
different data types for items, as explained in the text.

 

Being a python using person myself, I am not used to this, as arrays can
have any type of data in them, and there really isn't a 'record' type in
python that I am aware of. I think php is similar.

 

It would seem that this kind of structure is language dependent, and so not
the best for an exam question, in my opinion.

 

Guy Flaherty

Xavier College 

 

>>> "Laurie Savage" <savage.john.l at edumail.vic.gov.au> 18/08/10 01:57 PM >>>


I have a problem. In Fitzpatrick and Keane p. 161 (and in the 2007 exam)

arrays and records are primarily differentiated by data type. So the text

says: "An array is an indexed collection of elements of the same type of

data"; "A ... record represents a group of different data elements".

 

 

 

But, in PHP, this works:

 

 

 

<?php 

 

$pizzaToppings = array('onion', 'tomato', 'cheese', 'anchovies', 'ham',

'pepperoni', 1.6, 200); 

 

 

 

echo "<h1>We like $pizzaToppings[5] PIZZA!</h1>";

 

 

 

$num = $pizzaToppings[6] * $pizzaToppings[7];

 

echo $num;

 

?>

 

 

 

i.e. the array is storing data of different types and not storing the

numeric data as a string. What am I missing here? I've done a search, but

these are the only references I've seen that define this as the main

difference. I've been labouring under the delusion that an array lives in

volatile memory and disappears once the application halts or reinitialises

and a record is written to disk. I know from the web that I'm not alone

here.

 

 

 

Laurie Savage

 

Pascoe Vale Girls College

 

 

Important - This email and any attachments may be confidential. If received
in error, please contact us and delete all copies. Before opening or using
attachments check them for viruses and defects. Regardless of any loss,
damage or consequence, whether caused by the negligence of the sender or
not, resulting directly or indirectly from the use of any attached files our
liability is limited to resupplying any affected attachments. Any
representations or opinions expressed are those of the individual sender,
and not necessarily those of the Department of Education and Early Childhood
Development.

 

 

Scanned by Sonar. 

Date: 2010-08-18 14:05:08.466

From: sofdev-bounces at edulists.com.au

To: g.flaherty at xavier.vic.edu.au

Profile: Default_In

Mail id: challenge-2104307658s34-0

 

 

 

 

"This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the Network Manager
at Xavier College. Please note that any views or opinions presented in this
email are solely those of the author and do not necessarily represent those
of Xavier College. Whilst every attempt has been made to ensure material in
this email message is free from computer viruses or other defects, the
attached files are provided, and may only be used, on the basis that the
user assumes all responsibility for the use of the material transmitted."

 

_______________________________________________

http://www.edulists.com.au - FAQ, Subscribe, Unsubscribe

IT Software Development Mailing List kindly supported by

http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority
and

http://www.vcaa.vic.edu.au/vce/studies/infotech/softwaredevel3-4.html 

http://www.vitta.org.au  - VITTA Victorian Information Technology Teachers
Association Inc


Important - This email and any attachments may be confidential. If received
in error, please contact us and delete all copies. Before opening or using
attachments check them for viruses and defects. Regardless of any loss,
damage or consequence, whether caused by the negligence of the sender or
not, resulting directly or indirectly from the use of any attached files our
liability is limited to resupplying any affected attachments. Any
representations or opinions expressed are those of the individual sender,
and not necessarily those of the Department of Education and Early Childhood
Development.


Scanned by Sonar. 
Date: 2010-08-18 18:10:22.993
From: sofdev-bounces at edulists.com.au
To: g.flaherty at xavier.vic.edu.au
Profile: Default_In
Mail id: challenge-2119009392sy3-0



"This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the Network Manager
at Xavier College. Please note that any views or opinions presented in this
email are solely those of the author and do not necessarily represent those
of Xavier College. Whilst every attempt has been made to ensure material in
this email message is free from computer viruses or other defects, the
attached files are provided, and may only be used, on the basis that the
user assumes all responsibility for the use of the material transmitted."

_______________________________________________
http://www.edulists.com.au - FAQ, Subscribe, Unsubscribe
IT Software Development Mailing List kindly supported by
http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority
and
http://www.vcaa.vic.edu.au/vce/studies/infotech/softwaredevel3-4.html 
http://www.vitta.org.au  - VITTA Victorian Information Technology Teachers
Association Inc


Important - This email and any attachments may be confidential. If received in error, please contact us and delete all copies. Before opening or using attachments check them for viruses and defects. Regardless of any loss, damage or consequence, whether caused by the negligence of the sender or not, resulting directly or indirectly from the use of any attached files our liability is limited to resupplying any affected attachments. Any representations or opinions expressed are those of the individual sender, and not necessarily those of the Department of Education and Early Childhood Development.


More information about the sofdev mailing list