[Info-vax] Whither VMS?

[Bill Gunshannon]

In article <ha2o1t$jr4$2 at naig.caltech.edu>,
	glen herrmannsfeldt <gah at ugcs.caltech.edu> writes:
> Bob Eager <rde42 at spamcop.net> wrote:
> < On Thu, 01 Oct 2009 09:07:02 -0500, Bob Koehler wrote:
> <> In article <7ij0ueF30a3ujU4 at mid.individual.net>, Bob Eager
> <> <rde42 at spamcop.net> writes:
>  
> <>    Which makes you wonder why the inventors of C settled on such a
> <>    design in a day when CPUs were so much slower.  If I had a system
> <>    slower than a PDP-11/70, I'd have wanted it to spend it's time doing
> <>    better things.
>  
> < I never saw that that, in particular, caused any kind of performance 
> < problem. The libraries that used it were few - it's not often that you 
> < need to know the length of a string; more often you need to know when 
> < you've reached the end, and that is equally well served by a count or a 
> < terminator.
> 
> I have.  I have seen strcat() called inside a loop for building
> up a string while reading it in one line at a time.  The resulting
> algorithm is O(n**2).  (O(pow(n,2)) for C programmers.)  It was
> fast enough in testing, but in production the strings were millions
> of characters long and most of the time was spent in that loop.
>  
> < However, they didn't want a real limit on the lengths of strings. If 
> < they'd used a length prefix (as the predecessor to C did) they'd have had 
> < to make it two bytes, minimum. That would have used an extra byte per 
> < string, a waste of an even more valuable resource.
> 
> One result of null termination is the easy buffer overflow of
> many programs today that don't properly check lengths.  

And once again we blame the language for the incompetence (or just plain
laziness) of the programmers.

>                                                        Length
> at the beginning doesn't work so well if you want pointers to
> other than the beginning of a string.  The other way is with
> a structure containing a length and pointer, pretty much what
> Java does with String.

And one of the first languages that I used that had this "length byte"
concept was UCSD-Pascal.  Which, from the very start, included a way
to violate those bounds.  Go figure....

bill

-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
billg999 at cs.scranton.edu |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>