Re: Use of punctuation in a language?

On Saturday 08 Nov 2003 6:40 am, you wrote:
> there are many languages where "X := X + 1;" means something very
> different from "X := X - 1;", and there's only one character
> difference.


But both are assignment statements, both use the old value of X
to compute a new value, and both assign the new value to X.
They are not so VERY different.
The only difference is the operator used to compute the new value,
and the "+" or "-" is precisely what denotes the operator.


On the other hand, changing the comma to a full stop
on the right hand side of "DO 1 I=1,2" changes
the lexical analysis of the LEFT hand side from
"<keyword> <number> <identifier>" to "<identifier>"
and changes the statement from a loop to an assignment.


Another example is COBOL, where the addition or removal
of a full stop can change the structure of the whole program.


--
Martin


Martin.Ward@durham.ac.uk http://www.cse.dmu.ac.uk/~mward/

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