the program just output the amount of elements from array @a that are not in array @b
There's a recipe given in Programming Perl for this.

For default variable within loops- I think its not possible (atleast on Perl v5.8.9). I tried this:

@a=(11,22,33,44,55);
@b=(22,44,66,17);
foreach (@a) # $_ gets one value from @a
{
  @tested=grep {$_ == $::_} @b; # Had $_ been lexical for grep, $::_ w
+ould've been a global
}
print "\n@tested"; #Doesn't work as expected...$_ and $::_ both are sa
+me and get each value from @b
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Doesn't look like $_ can be made lexical to grep block.