"I see it as". If it's open to interpretation it's not that well self-documented :)
On 10/8/2010 5:54 PM, Brandon S Allbery KF8NH wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 10/8/10 13:48 , Michael Tiernan wrote: >> ----- "Tom Limoncelli"<t...@whatexit.org> wrote: >>> I see this in code now and then: >>> 1<<16-1 >> Being just a system geek and not a professional programmer, I don't >> understand why one would use that notation instead of the more obvious >> variations of "0x8000"? >> I understand that the compiler, at compile time (not run time) will figure >> out that the programmer "meant" 0x8000 from that piece of code so the end >> result is the same but it seems that for documentation purposes it'd be more >> obvious to do it the other way. >> Am I missing something? > I see it as a matter of self-documentation; "0x8000" suggests a magic number > of some kind, which is probably related to bits or to hardware control, > whereas "1<<(mumble)" explicitly says "this is a bit". (The former might be > a bit *mask*, or not linked to particular bits at all, for example a value > written to a control register where the register isn't documented at the bit > level but only the acceptable values.) Also, the "1<<n" syntax helps when > you are coding to a specification which describes things in terms of bit > numbers (e.g. "bit 0 controls the transmit register"). > > - -- > brandon s. allbery [linux,solaris,freebsd,perl] allb...@kf8nh.com > system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu > electrical and computer engineering, carnegie mellon university KF8NH > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v2.0.10 (Darwin) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iEYEARECAAYFAkyv52wACgkQIn7hlCsL25WN4wCghwyD0hLGLaV8P4UDUXtOj1S8 > KCsAoK4S6h/DBs4G7pp/WDRKkds844wn > =/va/ > -----END PGP SIGNATURE----- > _______________________________________________ > Tech mailing list > Tech@lopsa.org > http://lopsa.org/cgi-bin/mailman/listinfo/tech > This list provided by the League of Professional System Administrators > http://lopsa.org/ > _______________________________________________ Tech mailing list Tech@lopsa.org http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
