Re: [MacPerl] FNG

[rjk@linguist.dartmouth.edu (Ronald J. Kimball)]

Geoffrey C Kinnel wrote:
> 
> Ronald J. Kimball wrote:
> > 
> > As you can see, the failed match puts the special scalar SV_NO on the
> > stack.  Presumably, SV_NO comprises an integer value of 0 and a string
> > value of ''.  This explains the output of Chris's program with regards to
> > $w.
> > 
> > There is also an SV_YES, which is returned by print.
> 
> Would SV_NO be the same as \000, the ASCII null? I was poking around
> last night and found that "\000" exhibits properties similar to the
> return value from a failed s/// operation with regard to bitwise
> operators and the printf facility.

It's not so much that the answer is no; rather, I don't think that's quite
the right question to ask.  It's apples and oranges.

The special scalar SV_NO, we're assuming, comprises a numeric value of 0
and a string value of ''.  On the other hand, the ASCII character \000 is
neither a string nor a number.  You can put it in a string, as in "\000",
but then you have a string of length one.  SV_NO is a string of length 0,
so they can't be the same thing.

Note that ~"\000" gives you "\0377" rather than 0xffffffff.  If you ~ the
numeric value of "\000", which is 0, you would get 0xffffffff, though.


Ronald

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