I may be mistaken, but this does not detect a case like "}a{" , or does it? how about 
sub balanced { 
(my $s = shift) =~ s/[^()]//g; 
while ( $s =~s /\(\)// ){}; 
return $s ? 0 : 1; 
}

[download]
? It may be slower, but detects ')(' as incorrect

In reply to Re^2: Using qw to check for balanced parentheses by Anonymous Monk
in thread Using qw to check for balanced parentheses by unix_hacker_beard

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