Path: csiph.com!usenet.pasdenom.info!usenet.blueworldhosting.com!feeder02.blueworldhosting.com!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 18 Sep 2013 21:50:59 -0500 From: Scott Hemphill Newsgroups: comp.lang.postscript Subject: Re: [] [] eq apparently returns true References: <15de7a17-f979-4fe5-ac27-7215f68a4df6@googlegroups.com> Reply-To: hemphill@alumni.caltech.edu Date: Wed, 18 Sep 2013 22:50:59 -0400 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) Cancel-Lock: sha1:E2SSGS+Uzw/cH80M/zo8QQxb3cE= MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Lines: 28 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-ifdAVRLNs79TEoJi49z2p50odDYA+4QlKZl2qgOgbn9mYhWpNWbgLGOXYB8LTCEZqxO5J553vdkUIut!ltj92dtfeOJkCRX4VQ2fTTU0clYzf0mLS2DzHTNtYrYxwbg4cTXqjoQ= X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 1801 X-Received-Bytes: 1942 Xref: csiph.com comp.lang.postscript:1627 anavi8r@gmail.com writes: > Hi all, > > I am writing a PostScript interpreter and I just ran into the following strange issue: > > Apparently, a "standard" PostScript interpreter such as Photoshop, when running into the code > > [] [] eq > > returns true (which is unexpected), while the code > > [1] [1] eq > > or > > [] [1] eq > > return false (which is expected.) > > Why would two empty arrays considered equal? Shouldn't they still occupy different areas of the VM? Because empty arrays don't use any VM. The pointer into the VM is null. Scott -- Scott Hemphill hemphill@alumni.caltech.edu "This isn't flying. This is falling, with style." -- Buzz Lightyear