[Year 12 SofDev] Records and Arrays

[Laurie Savage]

Thanks Guy,

I'm glad I'm not alone. My girls have been confused about the issue when
doing revision, the brightest amongst them have twigged that that
distinction does not apply in PHP, so why is it set as a generalised
property of arrays/records? Mind you the others sit their and say "what's an
array again?"!

Laurie

-----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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Date: 2010-08-18 14:05:08.466
From: sofdev-bounces at edulists.com.au
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