sisters, bwothers,

Like the title says, undef is giving me horrible nightmares all of a sudden. I have two variables which I use in a for loop. At the end of that loop, I undef two variables, which are created at the beginning of the loop. Now, in one cycle, the two variables were not empty et al, and contained data from a previous loop... which of course caused lots of evil ;-)

my code looks something like this: 

for my $mode (@probe_modes) {
   my (@source,@destination);
   create_map_file $mode;
   get_elements; # @source and @destination are filled here
   scan_matrix $mode;
   undef(@source);
   undef(@destination);
}

[download]

I'm sure it's the undef that's causing the problem, because the first two subroutines should first check if the arrays need to be filled, and one will actually fill. The one that's checking reports that it's not going to fill (and it doesn't, i checked) and the second one says it's not filling, but there's data in the array of the previous loop.

I'm using: 

This is perl, v5.6.1 built for sun4-solaris-64int
(with 48 registered patches, see perl -V for more detail)

Summary of my perl5 (revision 5.0 version 6 subversion 1) configuratio
+n:
  Platform:
    osname=solaris, osvers=2.9, archname=sun4-solaris-64int
    uname='sunos localhost 5.9 sun4u sparc sunw,ultra-1'
    config_args=''
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef usemultipl
+icity=undef
    useperlio=undef d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=undef uselongdouble=undef
  Compiler:
    cc='cc', ccflags ='-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-xO3 -xdepend',
    cppflags=''
    ccversion='Sun WorkShop', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=87654321
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1
+6
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='of
+f_t', lseeksize=8
    alignbytes=8, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =''
    libpth=/lib /usr/lib /usr/ccs/lib
    libs=-lsocket -lnsl -ldl -lm -lc
    perllibs=-lsocket -lnsl -ldl -lm -lc
    libc=/lib/libc.so, so=so, useshrplib=true, libperl=libperl.so
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-R /usr/
+perl5/5.6.1/lib/sun4-solaris-64int/CORE'
    cccdlflags='-KPIC', lddlflags='-G'

[download]
Thanks !
--
to ask a question is a moment of shame
to remain ignorant is a lifelong shame

In reply to The weirdest problem with undef by insaniac

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