Date: Thu, 28 Aug 2014 16:15:27 +0300 From: Peter Pentchev <roam@ringlet.net> To: Vitaly Magerya <vmagerya@gmail.com> Cc: freebsd-hackers@freebsd.org, Chenguang Li <horus.li@gmail.com> Subject: Re: On changing rand(3) to random(3) in awk(1) Message-ID: <20140828131526.GA2385@straylight.m.ringlet.net> In-Reply-To: <53FEFBB8.5040305@gmail.com> References: <F70B9462-0898-47EF-AF83-47509F21F84E@gmail.com> <53FEFBB8.5040305@gmail.com>
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--RnlQjJ0d97Da+TV1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 28, 2014 at 12:51:52PM +0300, Vitaly Magerya wrote: > On 2014-08-28 09:21, Chenguang Li wrote: [snip] > >Index: run.c > >=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > >--- run.c (revision 270740) > >+++ run.c (working copy) > >@@ -1522,7 +1522,7 @@ > > break; > > case FRAND: > > /* in principle, rand() returns something in 0..RAND_MAX= */ > >- u =3D (Awkfloat) (rand() % RAND_MAX) / RAND_MAX; > >+ u =3D (Awkfloat) (random() % RAND_MAX) / RAND_MAX; >=20 > You should not use RAND_MAX with random(3), since it returns values > between 0 and 0x7fffffff (inclusive); RAND_MAX only applies to rand(3). >=20 > A better patch would be something like this: >=20 > >- /* in principle, rand() returns something in 0..RAND_MAX= */ > >- u =3D (Awkfloat) (rand() % RAND_MAX) / RAND_MAX; > >+ /* random() returns values in [0, 2147483647] */ > >+ u =3D (Awkfloat) random() / 2147483648; Hm. Since random() is documented to return "long", wouldn't it be a bit better with #include <limits.h> and LONG_MAX here? G'luck, Peter --=20 Peter Pentchev roam@ringlet.net roam@FreeBSD.org p.penchev@storpool.com PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint 2EE7 A7A5 17FC 124C F115 C354 651E EFB0 2527 DF13 --RnlQjJ0d97Da+TV1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBCAAGBQJT/ytqAAoJEGUe77AlJ98TAB0P/i+SiOsXSe5RYh19zSzVxvUB pXA5fMh2VGU69vT0cuy4aLgWzyyo6vX6fMMbuphYXRRa7RJIyf8XjqYnQPzKphP3 Xj3qs20kcFCPRUXr3LAM8kfOcGjGi++ZIDaEJSYpgqMGsmG7uWJ4cbv0LX6+HfxY 3GJTmBirvVENVwMOA+Rbd6WSH3+42+4eOJhXdtlQWbRB9SzhghIbCME8jMkPbXzS tsXKY3al7x8kYWhV/gQhffPUyFIjRfSe5uU0R9gVsUg5D1k9Z6s2bjX9UJtVAqBE OGYpHaOMffYFymJB8XE5MXHQzDbbOexsiD3v1JRWD7TLD/KaUgSkMiuhMM8I1Ynq Qec8Mnmpu40yI0ytTMuQl/Lbt/Ib/nVau5BBuI0HvdFm+jDXvnPtmo4OT5QDlUVt MOLP+DeN3Q8B9Z2+hV5FOZFPf9/t7w1gLV6c21t8Er9p1lzGP+rakNiT8cZUANVr kuFY/2E0EoYQYNFnOSgSTh9/twUj8Tyh/cOsPSmLUhp8Ol5rf73eNiorilQcbPmE /UU6AVrwhfaOXqjzbqP/JZ2u44sqQ3VNJBUnfSCEiKTu34/BC2Tax4S+/PluCK5n vLH8ICuAs/3MRzeZSZ+/tLCqvEhwstiSzYl4lr2Wvf+000W6uoi8bY6/cno7McBl OtdvZ/rL83V5qjFzGnvp =6Ojf -----END PGP SIGNATURE----- --RnlQjJ0d97Da+TV1--
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