[M3devel] Posix < 0 vs. # 0 vs. = -1?

[Mika Nystrom]

Jay K writes:
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>Posix often says:
>
> function foo() returns 0 for success=2C -1 for error
>
>=20
>
> m3core/libm3/etc=2C often say if foo() < 0 or if foo() # 0 "instead".
> Generally ok to tighten these up to "=3D -1"=2C perhaps upon checking manp=
>ages=2C
>  or a known rat's nest of inconsistencies?
>

Maybe this is just my personal style, but I would code it thus:

<*EXTERNAL*>
PROCEDURE F() : INTEGER; (* matches C declaration *)

...

VAR result : [0..1] := F(); (* matches man page specification *)
BEGIN
  CASE result OF 
    0 => ...
  |   
   -1 => ...
  END
END
   
No way for any sneaky value problems to get through.  The use of
CASE also guards against typos.

    Mika