>perl -wMstrict -le
"my @ra = (1,2,3,4,5);
 { $\" = undef;  print qq{@ra}; }
"
Use of uninitialized value in join or string at -e line 1.
12345

##</code><code>##

>perl -wMstrict -le
"my @ra = (1,2,3,4,5);
 { $\" = '';  print qq{@ra}; }
"
12345