Structure size

[Bruce.]

I would like to allocate a structure size of 1024 bytes but I want the
compiler to do the calculation for me.

typedef struct
{
int var1;
int var2;
int var3;
char var4[ ?????? ];
} MYSTRUCT;

What I want to do is replace the ?????? something that will automattically
make the total structure 1024 bytes without having to manually count the
bytes of the other members myself.

Is that possible in c++?

Thanks.

Bruce.

[Jerry Coffin]

In article <46************ ***********@new s.uslec.net>,
lr***@superlink .net says...

[ ... ]

It's backwards: the most common setup was 10 6-bit bytes in a 60-bit
word.

No. It was six bit characters. The bytes were 12 bits, the size of a PP
word.

Sorry -- I was using 'byte' as the C and C++ standards do -- to mean the
amount of storage needed for a character. For better or worse, people
have enough different meanings for "byte" that it's hard to be sure
what's meant without specifying...

--
Later,
Jerry.

The universe is a figment of its own imagination.

[LR]

Jerry Coffin wrote:

In article <46************ ***********@new s.uslec.net>,
lr***@superlink .net says...

[ ... ]

>>It's backwards: the most common setup was 10 6-bit bytes in a 60-bit
word.

No. It was six bit characters. The bytes were 12 bits, the size of a PP
word.

Sorry -- I was using 'byte' as the C and C++ standards do -- to mean the
amount of storage needed for a character. For better or worse, people
have enough different meanings for "byte" that it's hard to be sure
what's meant without specifying...

I understand, but the C++ standard says "Every byte has a unique
address." and that's a little difficult to apply to a machine (since we
included the 6600) whose CPU addresses 60 bit words. OTOH the PPs
could address 12 bit words.

Of course, we'd have to be careful about dealing with the character
instructions that were added to, I think, the Cyber 70s.

LR

[James Kanze]

On Jul 24, 11:05 pm, Jerry Coffin <jcof...@taeus. comwrote:

In article <1185310372.905 549.286...@k79g 2000hse.googleg roups.com>,
james.ka...@gma il.com says...

[ 'byte' on Control Data mainframes ... ]

Maybe. It's been a very, very long time. I seem to remember
something about 6 10 bit bytes in a 60 bit word. But that could
be completely wrong.

It's backwards: the most common setup was 10 6-bit bytes in a 60-bit
word.

But of course, an implementation of C couldn't use this
arrangement. (I was just guessing what C would look like on the
machine. The only program I actually ever wrote on it was in
Fortran.)

At any rate, as I said, it was a long time ago, so memory could
be playing any sort of tricks on me. And it didn't seem worth
the bother of looking it up, since I rather doubt I'll have to
write code for that machine anytime in the near future:-).

--
James Kanze (GABI Software) email:ja******* **@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[Jerry Coffin]

In article <46************ ***********@new s.uslec.net>,
lr***@superlink .net says...

[ ... ]

I understand, but the C++ standard says "Every byte has a unique
address." and that's a little difficult to apply to a machine (since we
included the 6600) whose CPU addresses 60 bit words. OTOH the PPs
could address 12 bit words.

C and C++ both require a minimum of 8 bits for characters in any case.

As far as addressing goes, you'd (probably) do about like most C
compilers for the Cray did: a pointer to the word along with a small
integer specifying a character in the word. It's been a long time, but
if memory serves that's roughly how a pointer to char in Pascal 6000 was
implemented.

--
Later,
Jerry.

The universe is a figment of its own imagination.

[Jerry Coffin]

In article <11************ **********@q75g 2000hsh.googleg roups.com>,
ja*********@gma il.com says...

[ CDC mainframes ... ]

At any rate, as I said, it was a long time ago, so memory could
be playing any sort of tricks on me. And it didn't seem worth
the bother of looking it up, since I rather doubt I'll have to
write code for that machine anytime in the near future:-).

Should you get an irresistible urge to do so, Google for "dtcyber", and
you'll find there's a fairly accurate emulator for it that runs under
Windows...

--
Later,
Jerry.

The universe is a figment of its own imagination.

[LR]

Jerry Coffin wrote:

In article <11************ **********@q75g 2000hsh.googleg roups.com>,
ja*********@gma il.com says...

[ CDC mainframes ... ]

>At any rate, as I said, it was a long time ago, so memory could
be playing any sort of tricks on me. And it didn't seem worth
the bother of looking it up, since I rather doubt I'll have to
write code for that machine anytime in the near future:-).

Should you get an irresistible urge to do so, Google for "dtcyber", and
you'll find there's a fairly accurate emulator for it that runs under
Windows...

Is there a COMPASS ng for any questions that come up? ;)

LR

[Jerry Coffin]

In article <46************ ***********@new s.uslec.net>,
lr***@superlink .net says...

[ ... ]

Is there a COMPASS ng for any questions that come up? ;)

None of which I'm aware...nor (TTBOMK) are there any NGs for Scope, NOS,
NOS/VE, etc.

--
Later,
Jerry.

The universe is a figment of its own imagination.