Subj : Re: Dartmouth BASIC to C
To   : comp.programming
From : spinoza1111
Date : Sat Aug 13 2005 04:22 am


John Smith wrote:
> spinoza1111@yahoo.com wrote:
> > Looks great, with a minor cavil.
> >
> > You simulate Dartmouth Basic's READ/DATA facility which would give a
> > system error message if there was not enough DATA to READ in the pool
> > of DATA.
>
>  From page 6 of the manual:
>
> "After commpleting the computation for the second set of right hand
> sides and printing the answers, the computer will give the last values,
> 4 and -7, to the variable B1 and B2, compute and print the third set of
> answers, and then stop, because there is no more data when the READ
> statement 30 is encountered for the fourth time."
>
> and page 27:
>
> "Each time a READ statement is encountered anywhere in the program, the
> data block supplies the next available number or numbers. If the data
> block runs out of data, with a READ statement still asking for more, the
> program is assumed to be done."
>
> My understanding of this is that the result of a READ after data are
> exhausted is normal termination, not an error. I don't remember whether
> this was the case with later flavors of BASIC, for example, the MS
> Basics. I'll have to trot out my copy of qBasic and give it a try.

Hmm, the compiler in my book (Build Your Own .Net Language and
Compiler) produces an error message.

You'll have to explain to me how you can terminate "normally" when a
READ DATA statement is executed, for example inside a For loop. If no
error message is provided, this isn't normal termination. Instead, it's
partial output and an unexplained termination.

However, this is better than the C program which will, I think, read
values from random memory locations.
> 
> JS

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