[Year 12 SofDev] Records and Arrays

[Mark KELLY]

Even *realer* men use COBOL rather than COBAL  :-)

On 20 August 2010 10:36, John Schwartz <jschwartz at parade.vic.edu.au> wrote:

> Nope! Real men use COBAL via punched 80 column cards and rarely actually
> see the computer.
> John
>
> John Schwartz
> Parade College
> 1436 Plenty Road
> Bundoora, Victoria, 3083
> Phone: 03 9468 3300
> Fax: 03 9467 3937
> e-mail: jschwartz at parade.vic.edu.au
> web: www.parade.vic.edu.au
>
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> -----Original Message-----
> From: Laurie Savage [mailto:savage.john.l at edumail.vic.gov.au]
> Sent: Friday, 20 August 2010 10:23 AM
> To: 'Year 12 Software Development Teachers' Mailing List'
> Subject: Re: [Year 12 SofDev] Records and Arrays
>
> Rubbish, real men use COBOL! On green screens running on a daisy chain
> network with the CTOS/Unisys OS.
>
> Reminds me of a lovely Dilbert cartoon of two old geezers reminiscing about
> the days when all you needed to program was ones and zeroes.
>
> Laurie
>
> Written from brown paper bag in t'swamp using a Remington typewriter.
>
> -----Original Message-----
> From: sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au]
> On Behalf Of Don Morelli (Optus)
> Sent: Friday, 20 August 2010 9:52 AM
> To: 'Year 12 Software Development Teachers' Mailing List'
> Subject: Re: [Year 12 SofDev] Records and Arrays
>
> I am sure that I used Knuth when I did Information Science in 1972 (could
> be
> wrong as I couldn't actually find the book) and I don't know why you guys
> use these new fandangled programming languages the blur old well understood
> distinctions, as the catch cry in the 70's and mid 80's and should still
> be,
> "Real men use Fortran"
> Cheers Don :)
>
> -----Original Message-----
> From: sofdev-bounces at edulists.com.au [mailto:
> sofdev-bounces at edulists.com.au]
> On Behalf Of Kevork Krozian
> Sent: Thursday, 19 August 2010 11:13 PM
> To: 'Year 12 Software Development Teachers' Mailing List'
> Subject: Re: [Year 12 SofDev] Records and Arrays
>
> Hi Guy,
>
>  Wow this is really getting interesting !!!  No, I mean it .... :))
>
> I wouldn't dare argue with Knuth especially since he was the author of my
> Computer Science 101 text at Monash Uni in 1981 .. but
>
> Check out
> http://en.wikipedia.org/wiki/Enumerated_type
>
> specifically look for the line:
>
> Pascal style languages also allow for enumeration to be used as array index
> type
>    cardsuit = (clubs, diamonds, hearts, spades);
> var
>    suitcount: array [cardsuit] of integer;
>
> I used this enumerated type as the index for many arrays in my early years
> using Pascal such as
>
> type
>    month = (jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec);
> var
>    rainfall: array [month] of real;
> Also, quoting further from the Wikipedia source above,
> "
> The order in which the enumeration values are given matters. An enumerated
> type is an ordinal type, and the pred and succ functions will give the
> prior
> or next value of the enumeration, and ord can convert enumeration values to
> their integer representation. Standard Pascal does not offer a conversion
> from arithmetic types to enumerations, however. Extended Pascal offers this
> functionality via an extended succ function. Some other Pascal dialects
> allow it via type-casts. Some modern descendants of Pascal, such as
> Modula-3, provide a special conversion syntax using a method called VAL;
> Modula-3 also treats BOOLEAN and CHAR as special pre-defined enumerated
> types and uses ORD and VAL for standard ASCII decoding and encoding."
>
> Admittedly I have neither tried or investigated this implementation with
> other languages but Delphi users out there can perhaps tell us if it is
> also
> found in that implementation since the VCAA advice refers to Pascal and
> similar languages such as Delphi.
>
>
> Kind Regards
>
> Kevork Krozian
> Edulists Creator Administrator
> www.edulists.com.au
> tel: 0419 356 034
>
>
> -----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 11:01 PM
> To: sofdev at edulists.com.au
> Subject: Re: [Year 12 SofDev] Records and Arrays
>
> Kevork,
>
> Wikipedia states that the index for an array is an integer based one and
> provides references from Donald Knuth and Paul E. Black to support this.
> It states that this index is required to be used when calculating the
> address of the memory location for each item in the array. This actually
> is explained to be one of the general differentiators between an array
> and a record, in that an array's memory addresses can be computed at
> run-time using the integer index and a record's cannot be easily
> computed at run-time.
>
> I think it would be a brave list to argue against Knuth ;) I am not sure
> if I am helping anyone here :D
>
> Guy Flaherty
>
> >>> "Kevork Krozian"  19/08/10 10:05 PM >>>
> Hi Folks,
>
>
>
>  Just watching from the sidelines at present and having a feeling of déjà
> vu. There are quite a few examples of definitions that have
> disadvantaged my
> students in the past not least in the role and functions of  networking
> components (hubs vs switches, modems and routers and firewalls and virus
> protection etc )  as well as data types in programming definitions.
>
> The last time I used Pascal was around 1995 or so at least in so far as
> programming at Year 12.
>
> Sure I used records of files but more commonly found records as a single
> line in a database which we are not allowed to use in our programming. I
> haven't heard of a file of records for many years - only a database of
> records. Perhaps, I will leave that discussion for another time.
>
>
>
> More generally and this is related to the definition used by Adrian here
> ,
> the index for an array does not have to be an integer. It can be any
> enumerated type eg. Inbuilt ones such as characters defined by say the
> ASCII
> sequence, meaning 'a' , 'b' , 'c' ,'d' etc can be used to index an array
> or
> a user defined enumerated range eg. 'Jan', 'Feb' , 'Mar', 'Apr' etc can
> also
> be used to index an array.
>
>
>
> I also come from the Fortran, Pascal, Cobol, C, Prolog, Java, PHP,
> Python,
> Visual C# pathway in my programming development and have had to make the
> transition into new areas of programming where the older definitions are
> no
> longer uniformly found in all languages. That would be the evolution of
> programming and the blurring of the definitions of data types akin to
> the
> analogy of applications that blur the lines that used to separate them (
> think Word Processors, spreadsheets and databases).
>
>
>
> Take Care
>
>
>
> Kevork Krozian
>
> Edulists Creator Administrator
>
> www.edulists.com.au
>
> tel: 0419 356 034
>
>
>
> 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
>
>
> Website: http://www.mhs.vic.edu.au
>
> Blog: 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
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> Date: 2010-08-19 22:03:35.610
> From: sofdev-bounces at edulists.com.au
> To: g.flaherty at xavier.vic.edu.au
> Profile: Default_In
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-- 
Mark Kelly
Manager - Information Systems; Reporting Manager
McKinnon Secondary College
McKinnon Rd McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085
School Phone +613 8520 9000, Fax +613 9578 9253
kel at mckinnonsc.vic.edu.au

Webmaster - http://www.mckinnonsc.vic.edu.au
Author - VCE IT Lecture notes: http://vceit.com
Moderator: IT Applications Mailing List

Korma: the philosophy that what you get out of a curry depends on what you
put into it.
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