Re: C style assignment of variable values

[Jim Langston <jlangston@xxxxxxxxxxxxxxxx>]

EVAL A, B, C = 0
I like.  I can understand what that is doing.

I remember seeing an expression in basic
a = b = c = e = f = 0
and I hated that.  Because = can be boolean or an equation.

(couldn't that be saying, if F = 0 and E = (F = 0) and C = (E = (F = 0)) etc..
and evaluate to true or false and be applied to a? as hans says?)

Regards,

Jim Langston

boldt@ca.ibm.com wrote:

> <SNIP>
> Unfortunately, the = operator is overloaded in RPG IV.  It's used
> for both assignment and comparison.  The above EVAL statement is
> almost valid today.  Replace it with, say:
>
> EVAL    A = B = C
>
> and you'd have a valid RPG IV statement.  It wouldn't do what you
> expected, though.  First, expression B = C would be evaluated
> giving an indicator value.  The result of that comparison would
> then be assigned to A.
>
> The main issue here is that in RPG IV, assignment is considered a
> statement.  But in other languages, like C and Perl, it is an
> expression.  With assignment as an expression, you run into such
> messy issues like order of evaluation and side effects.  (Not to
> mention the common C bug: if(a=b)!)
>
> OTOH, we could possibly come up with some different syntax like:
>
> EVAL    A, B, C = 0
>
> Cheers!  Hans
>
> Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
>
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