in reply to checking array elements aginst another array

You cannot have more than one statement modifier, and you can't make up syntaxt :) 
die "Unknown char! \n" unless exists $testHash{$_} for (@test);

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is better written as 
die "Unknown char! \n" unless grep { exists $testHash{$_} } @test;

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Re^2: checking array elements aginst another array
by AnomalousMonk (Archbishop) on May 08, 2009 at 12:28 UTC
    ... better written as
       die "Unknown char! \n" unless grep { exists $testHash{$_} } @test;
    This will only  die when none of the characters in the test string are 'known': 
    >perl -wMstrict -le
"my %testHash = map { $_ => 1 } 'a' .. 'j';
 for my $str (@ARGV) {
   my @test = split '', $str;
   die qq{unknown char in '$str'}
     unless grep { exists $testHash{$_} } @test;
   print qq{'$str' ok};
   }
"  abcd  axyz  xyz
'abcd' ok
'axyz' ok
unknown char in 'xyz' at -e line 1.

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    A better way to write this (assuming something like Array::Diff is not acceptable) might be:
        exists $testHash{$_} or die "Unknown char! \n" for @test;
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