Hello, I am seeing some strange behavior (strange to me at least). An array (@plist) in my perl script seems to be getting stomped on after I execute a function (ccmexec_nodie), which has no relation to said array. (no reference is ever passed to that function). However, after every call to this function, an additional element of my array gets overwritten by "undef".

Here is an example from a debugger session: 

227:                            my $cvidPredessor = ccmexec_nodie("ccm
+ query -type project -name $projectName -version $predessorVersion -f
+ %cvid -u");
  DB<3> x @plist
0  undef
1  'PROTOSIM_PrototypeSpacecraftSimulation 13755 1'
  DB<4> n
main::UpdateSubProjects(subProjectSetup.pl:228):
228:                            chomp($cvidPredessor);
  DB<4> x @plist
0  undef
1  undef
  DB<5>

[download]

Note that @plist changes after executing the call to ccmexec_nodie on line 227, although it doesn't appear anywhere on that line. Infact, all I am passing to ccmexec_nodie is a string. I started seeing this behavior after using IPC::Open3 in ccmexec_nodie. I don't have any experience using this before, the reason I am using it now rather than backticks is to capture both the stdout and stderr of the system command I am executing. Thoughts?

Here is the contents of ccmexec_nodie: 

sub ccmexec_nodie
{
    my $command = $_[0];
    
    myprint(2,"\t\t\tccmexec: $command\n");
    
    my ($mystdin,$mystdout,$mystderr);
    my $pid = open3($mystdin,$mystdout,$mystderr,$command);
    
    my $myresult = "";
    while(<$mystdout>){
        $myresult = "$myresult$_";
    }
    
    return $myresult;
}


sub myprint{
    my $level = $_[0];
    my $string = $_[1];
    
    if($level <= 1){
        print $string;
    }        
}

[download]

In reply to Why are elements of my array getting deleted? by iKnowNothing

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.