I learned something today. I thought that with my @x; @x would be undefined but with my @x = (); @x would be a defined but empty list. I guess I was wrong. Here is the experiment I ran. I

my @x;
print 'my @x;',"\n"; &checkdef;
@x = ();
print '@x = ();',"\n"; &checkdef;
@x = (1);
print '@x = (1);',"\n"; &checkdef;
@x = ();
print '@x = ();',"\n"; &checkdef;
undef @x;
print 'undef @x;',"\n"; &checkdef;
@x = ();
print '@x = ();',"\n"; &checkdef;
sub checkdef {
    if (defined (@x)) {
        print "\@x is defined\n"
    } 
    else {
        print "\@x is undefined\n"
    }

}
__OUTPUT__
my @x;
@x is undefined
@x = ();
@x is undefined
@x = (1);
@x is defined
@x = ();
@x is defined
undef @x;
@x is undefined
@x = ();
@x is undefined
[download]

Is anyone else surprised by the results?

--

flounder

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.