SV: Re: New Book: The School of Niklaus Wirth

> The real "serious" descendent of Pascal, Ada, brings signed and
> unsigned types for all these lengths...


Actually, Ada83 did not define an unsigned type, which made the
language a pain to use for systems oriented tasks such as linkers,
etc. An unsigned type was added to Ada9x, however.


Ada9x also added another "basic integer" type - the modulo type, which
is a kind of "unsigned wrap-around type", which is an integer that
silently wraps around when it reaches the modulo value (without
throwing an exception).


So instead of writing the code shown below in C:


uint Index;
            ...
            Index += 1;
            Index %= TableSize;
...


You'd write the code shown below in Ada95 (or something like it; I
haven't looked at Ada for a few years):


...
Index is mod TableSize;
begin
...
Index = Index + 1
...
end




-- Mikael

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