Re: What is the history behind Natural'First = 0 ?

[Keith Thompson <Keith.S.Thompson+u@gmail.com>]

Robert A Duff <bobduff@TheWorld.com> writes:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> Wikipedia says that some definitions have "natural numbers" starting
>> with 0, and others have them starting with 1 -- and the term "whole
>> numbers" is sometimes used to refer to the set of all integers.
>
> "The nice thing about standards is that there are so many to choose from."
>
> I seem to recall an early version of Ada (or Green) that said
> "subtype Natural is Integer range 1..Integer'Last;".  I could
> be misremembering that, and (if true) I don't remember what the
> 0..Integer'Last one was called.

Yes, I remember that.  I found a copy of the 1979 Preliminary Ada
Reference Manual from SIGPLAN Notices, June 1979 at

    https://dl.acm.org/doi/pdf/10.1145/956650.956651

The section covering package STANDARD says:

    subtype NATURAL is INTEGER range 1 .. INTEGER'LAST;
    type STRING is array (NATURAL) of CHARACTER;

There was no predefined subtype starting at 0.  I don't know just when
NATURAL was changed to start at 1 and POSITIVE was introduced.

(And I'm glad they decided to stop using ALL_CAPS for identifiers).

> Speaking of zero:
>
> Q: What caused the fall of the Roman Empire?
> A: They didn't know about zero, so they had no way to terminate
> the strings in their C programs.  Har, har.

But it wasn't all that bad, since they only had 100 programs.

A Centurion walks into a bar.  He holds up two fingers.  "Five beers, please."

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */