If $var1 has the value 0, it will be set to '', which might not be what you want.

Mh... something like this?

@x=(1..3) ;
undef $x[1] ;
$_ = defined $_? $_: '[__UNDEF__]' for @x ;
print "@x" ;
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Ciao!
--bronto

---

The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway).
--John M. Dlugosz

or like this:

$_ = '[undef]' for grep !defined, $var1, $var2, $var3;
print "$var1, $var2, $var3";
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Update: I forgot that changing the values can affect program logic(as Aristotle mentioned). So, the best approach (imho) is just print with warnings or

use Data::Dumper;
print Data::Dumper->Dump([$var1, $var2, $var3], [qw(var1 var2 var3)]);
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If the values might be uninitialized in the normal course of operation, and it's acceptible, then I see no problem just turning off the warning, as the OP has done. This is Perl, after all. The language should do what we want, not the other way around. :-)