On Thu, 2 Mar 2017 16:35:17 -0600
Andy Bach <afb...@gmail.com> wrote:
> if ( not defined $interdest5 ) ...
>
> defined() is the built in function. "undef" is a value ... not sure
> why you don't get a syntax error there but, most likely, the if quits
> at seeing "undef" as it's "false"
>
> perl -we 'if (undef $interdest5) {$interdest5 = "";} print
> "$interdest5\n"' Use of uninitialized value $interdest5 in
> concatenation (.) or string at -e line 1.
>
> $ perl -we 'if (undef $interdest5) {$interdest5 = "";} print "i:
> $interdest5\n"'
> Use of uninitialized value $interdest5 in concatenation (.) or string
> at -e line 1.
> i:
> $ perl -we 'if (undef eq $interdest5) {$interdest5 = "";} print "i:
> $interdest5\n"'
> Use of uninitialized value in string eq at -e line 1.
> Use of uninitialized value $interdest5 in string eq at -e line 1.
> i:
> $ perl -we 'if (undef == $interdest5) {$interdest5 = "";} print "i:
> $interdest5\n"'
> Use of uninitialized value $interdest5 in numeric eq (==) at -e line
> 1. Use of uninitialized value in numeric eq (==) at -e line 1.
> i:
>
> Hah! "undef" is an uninitialized value !
$ perl -we 'if (not $interdest5) {$interdest5 = "";} print
"|$interdest5|\n"'
||
$ perl -we 'if (! $interdest5) {$interdest5 = "";} print
"|$interdest5|\n"'
||
--
Don't stop where the ink does.
Shawn H Corey
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
