Re^3: Fucking sprintf rounding - how does it work?

[daxim]

in reply to Re^2: Fucking sprintf rounding - how does it work?
in thread F***ing sprintf rounding - how does it work?

Certainly.

$ perl -e'printf qq[%s => %.68f => %.1f\n], (qq[0.${_}5]) x 3 for (0..
+9)'
0.05 => 0.050000000000000000000677626357803440271254658000543713569641
[phone] => 0.1
0.15 => 0.150000000000000000005421010862427522170037264004349708557128
[phone] => 0.2
0.25 => 0.250000000000000000000000000000000000000000000000000000000000
+00000000 => 0.2
0.35 => 0.349999999999999999994578989137572477829962735995650291442871
+09375000 => 0.3
0.45 => 0.449999999999999999989157978275144955659925471991300582885742
[phone] => 0.4
0.55 => 0.550000000000000000010842021724855044340074528008699417114257
[phone] => 0.6
0.65 => 0.649999999999999999978315956550289911319850943982601165771484
[phone] => 0.6
0.75 => 0.750000000000000000000000000000000000000000000000000000000000
+00000000 => 0.8
0.85 => 0.850000000000000000021684043449710088680149056017398834228515
[phone] => 0.9
0.95 => 0.949999999999999999989157978275144955659925471991300582885742
[phone] => 0.9

$ perl -V

Summary of my perl5 (revision 5 version 16 subversion 0) configuration
+:

  Platform:
    osname=linux, osvers=3.1.10-1.9-desktop, archname=x86_64-linux-thr
+ead-multi-ld
    uname='linux champion 3.1.10-1.9-desktop #1 smp preempt thu apr 5 
+18:48:38 utc 2012 (4a97ec8) x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/daxim/local/share/perlbrew/perls/p
+erl-5.16.0 -DDEBUGGING -Dusemorebits -Dusethreads -Dcf_email=daxim@cp
+an.org -Dperladmin=[e-mail] -Accflags=-fPIC'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=und
+ef
    use64bitint=define, use64bitall=define, uselongdouble=define
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fPIC -DDEBUGGING -f
+no-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LA
+RGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fPIC -DDEBUGGING -fno-strict
+-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.6.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1
+6
    ivtype='long', ivsize=8, nvtype='long double', nvsize=16, Off_t='o
+ff_t', lseeksize=8
    alignbytes=16, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/../lib64 /usr/lib/../lib64 /lib /usr/li
+b /lib64 /usr/lib64 /usr/local/lib64
    libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -l
+c -lgdbm_compat
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=/lib/libc-2.15.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.15'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib -fs
+tack-protector'


Characteristics of this binary (from libperl):
  Compile-time options: DEBUGGING HAS_TIMES MULTIPLICITY PERLIO_LAYERS
                        PERL_DONT_CREATE_GVSV PERL_IMPLICIT_CONTEXT
                        PERL_MALLOC_WRAP PERL_PRESERVE_IVUV
                        PERL_TRACK_MEMPOOL USE_64_BIT_ALL USE_64_BIT_I
+NT
                        USE_ITHREADS USE_LARGE_FILES USE_LOCALE
                        USE_LOCALE_COLLATE USE_LOCALE_CTYPE
                        USE_LOCALE_NUMERIC USE_LONG_DOUBLE USE_PERLIO
                        USE_PERL_ATOF USE_REENTRANT_API
  Built under linux
  Compiled at May 22 2012 09:25:33
  %ENV:
    PERLBREW_BASHRC_VERSION="0.42"
    PERLBREW_HOME="/home/daxim/.perlbrew"
    PERLBREW_MANPATH="/home/daxim/local/share/perlbrew/perls/perl-5.16
+.0/man"
    PERLBREW_PATH="/home/daxim/local/share/perlbrew/bin:/home/daxim/lo
+cal/share/perlbrew/perls/perl-5.16.0/bin"
    PERLBREW_PERL="perl-5.16.0"
    PERLBREW_ROOT="/home/daxim/local/share/perlbrew"
    PERLBREW_VERSION="0.42"
  @INC:
    /home/daxim/local/share/perlbrew/perls/perl-5.16.0/lib/site_perl/5
+.16.0/x86_64-linux-thread-multi-ld
    /home/daxim/local/share/perlbrew/perls/perl-5.16.0/lib/site_perl/5
+.16.0
    /home/daxim/local/share/perlbrew/perls/perl-5.16.0/lib/5.16.0/x86_
+64-linux-thread-multi-ld
    /home/daxim/local/share/perlbrew/perls/perl-5.16.0/lib/5.16.0
    .