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<DIV><FONT face=Arial size=2>Hello Damien</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>First, I'm not sure that how the various data types
are physically stored is part of the study design - at least, I can't see it
anywhere.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Second, one reason for the different storage sizes
is probably historical as much as anything. For example, C was developed on
PDP-11 which was a 16-bit minicomputer, so 2 bytes as basic int storage makes
sense. C++, coming along later as it did, was probably first developed on a
32-bit machine. I wouldn't be surprised if VB.NETs owes its 2-byte integers to
its ancestor quickBASIC, originally written for 8088/86 machines.The other
number types would have a similar heritage.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>As for char, 1 byte accomodates ASCII, while 2
bytes accomodates Unicode. I don't know why, but MS was one of the early
adopters of Unicode, possibly because of its flagship product MS Word, so
building chars on 2 bytes would have been a logical step for
them.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The boolean data type is the interesting one.
In principle it only needs one bit, but fetching a single bit from memory can be
very inefficient, depending on how the memory system is designed. That leads to
1 byte storage on older machines since it's more efficient to store a byte than
a bit (0000 0000 or 1111 1111), although I'm not sure how that translates
to 32-bit machines!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Regards</FONT></DIV>
<DIV><FONT face=Arial size=2>Robert T-A</FONT></DIV>
<DIV> </DIV>
<DIV>----- Original Message ----- </DIV>
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<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=Damien.ATKINSON-BUCK@ivanhoe.com.au
href="mailto:Damien.ATKINSON-BUCK@ivanhoe.com.au">ATKINSON-BUCK, Damien</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=sofdev@edulists.com.au
href="mailto:sofdev@edulists.com.au)">Year 12 Software Development Teachers'
Mailing List(sofdev@edulists.com.au)</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 31, 2013 3:42 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [Year 12 SofDev] Data Type
Sizes</DIV>
<DIV><BR></DIV>
<DIV class=WordSection1>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial','sans-serif'">Hi folks,
</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Arial','sans-serif'">
I’ve been working through various data dictionaries with my students and the
issue of data type sizes, somebody pointed out a difference between the text
and what VB.NET state, so I decided to do a bit of research into various
languages and see what they store data as. Attached are the results. It’s OK
for SACs as we can base that on the language we’re using, but just wondering
what the official VCAA size might be – and if anyone can explain the reasons
for the difference (I assume it’s due to various compilation methods, but the
brain is too fried to go into too much). Also, anyone out there using the
languages that I have blank fields on that could fill them in?</SPAN></P>
<P class=MsoNormal><SPAN
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<P class=MsoNormal><SPAN
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