[Year 12 SofDev] Records and Arrays

Wed Aug 18 17:58:05 EST 2010

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

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