Path: utzoo!attcan!uunet!husc6!mailrus!iuvax!bsu-cs!cfchiesa From: cfchiesa@bsu-cs.UUCP (Christopher Chiesa) Newsgroups: comp.os.vms Subject: Re: Thanks for the replies, and Quadword Date Comparisons Summary: Date comparisons... Message-ID: <3379@bsu-cs.UUCP> Date: 5 Jul 88 19:04:34 GMT References: <8806281323.AA07688@mitre-bedford.ARPA> Organization: CS Dept, Ball St U, Muncie, Indiana Lines: 32 In article <8806281323.AA07688@mitre-bedford.ARPA>, mhg@MITRE-BEDFORD.ARPA (Mark H. Granoff) writes: > > My application stores date/time stamps for certain events in quadword > format. I would like to have commands that use qualifiers like > /SINCE=date and /BEFORE=date (like the VMS DIRECTORY command, etc). > My question is: What's the best way to do date comparison like this? > I thought of a couple ways: > > 1. Call LIB$SUBX with the two dates. Based on the sign of the > > 2. Use LIB$DAY (I think), which returns the day number of a given > > Is there a better way? Are these two solutions reasonable, > interchangable, did I miss something in a manual or something, or ....? This may generate more questions than it answers, but... ... can't you just compare your quadwords directly? Now wait, I don't mean using a nonexistent "CMPQ" instruction; I mean, using the appropriate combination of two CMPL instructions, is it not the case that the date/time quadwords simply INCREASE as time goes by? I.e. that the date/time quad- word of a LATER date will always be greater than that for an EARLIER date? I've done a little experimenting along this line and this has always seemed to be the case. Chris Chiesa -- UUCP:!{iuvax,pur-ee,uunet}!bsu-cs!cfchiesa cfchiesa@bsu-cs.UUCP