RE: [BLACKBOX] Variable initialization in BlackBox

From: null <">
Date: Thu, 09 Oct 2008 08:09:43 +0000

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Hi Chris,

[...]
>
> If values are to be initialised then <undefined> would be a
> better initial value. Any subsequent access to a variable
> with an undefined value should then cause a system trap to
> identify it. As far as I remember CDC Pascal 6000 that

yes, absolutely. But that was a feature of the CDC linker,
which initialized data areas with <undefined> by default.
It was possible to explicitely request initialzing to <zero>.

I remember porting a Fortran IV program from an IBM mainframe
to a CDC which had after more than 10 years of usage on the IBM
the questionable statement

        IF (I .EQ. O) ...

where the variable named with letter O was initialized to zero
and therefore did the intended comparison with zero.

CDC by default initialized with <undefined> and crashed upon
read access of the uninitialzed variable.

regards
    Bernhard

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Received on Thu Oct 09 2008 - 10:09:43 UTC