Not so much a serious syntax error as a serious semantic error. You are creating a string using qq where what you really want is a list of characters. To compound the problem qq interpolates so $, (the output field separator special variable) is interpolated but generates a 'Use of uninitialized value in concatenation (.) or string at ...' warning because it is undef by default.

You can achieve what you intend with:

use warnings;
use strict;

my @chars = ('a'..'z', 'A'..'Z', '0'..'9', '!', '@', '#', '$', '%', '^
+', '&', '*');

print @chars;
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Prints:

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*
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