develooper Front page | perl.perl5.porters | Postings from December 2003

[perl #24735] Possible documentation incompleteness or bug in the range operator on undef

Thread Next
December 23, 2003 20:18
[perl #24735] Possible documentation incompleteness or bug in the range operator on undef
Message ID:
# New Ticket Created by 
# Please include the string:  [perl #24735]
# in the subject line of all future correspondence about this issue. 
# <URL: >

rl This is a bug report for perl from,
generated with the help of perlbug 1.34 running under perl v5.8.0.

[Please enter your report here]

This is expected:
perl -le '$to=""; @a="B"..$to; print "<@a>"'

.. is supposed to magic increment B until it's longer than 
the endvalue ("", which is not in the range). Since this is
so already for the first value, you get the empty list. Good.

This was unexpected:
perl -le '$to=undef; @a="B"..$to; print "<@a>"'
What I suppose is happening here is that not *both* operands are
strings, and so it's doing a numeric .., and B and undef in a
numeric context are both 0, so I'm really doing 0..0 and get 0.

But why is it seeing undef as the number 0 and not the string
"" ? In other operators that change behaviour as soon as *one* of the
arguments is a number, like |, undef actually behaves like a string:

perl -le '$to=undef;print "B"|$to'

[Please do not change anything below this line]
Site configuration information for perl v5.8.0:

Configured by ton at Tue Nov 12 01:56:18 CET 2002.

Summary of my perl5 (revision 5.0 version 8 subversion 0) configuration:
    osname=linux, osvers=2.4.19, archname=i686-linux-thread-multi-64int-ld
    uname='linux quasar 2.4.19 #5 wed oct 2 02:34:25 cest 2002 i686 unknown '
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=undef uselongdouble=define
    usemymalloc=y, bincompat5005=undef
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -fomit-frame-pointer',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='2.95.3 20010315 (release)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long long', ivsize=8, nvtype='long double', nvsize=12, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lndbm -ldb -ldl -lm -lpthread -lc -lposix -lcrypt -lutil
    perllibs=-lnsl -ldl -lm -lpthread -lc -lposix -lcrypt -lutil
    libc=/lib/, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:

@INC for perl v5.8.0:

Environment for perl v5.8.0:
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

Thread Next Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About