my $text = '0101010101';
my %hash;
@hash{ split '', $text } = 1;
print scalar keys %hash, "\n";

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Although this code above will work correctly, it will not be doing so the way that you expected which could lead you to trouble. 
@hash{@array} = $scalar

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only sets $scalar as the value for the first key in %hash. To set all the keys, you'd want to do something like: 
@hash{@array} = ($scalar) x scalar @array;

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In the actual code above, since you don't check values anyway, you can just write: 
@hash{@array} = ();

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In reply to Re: Re: Re: number of unique characters in a string by genecutl
in thread number of unique characters in a string by Anonymous Monk

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