Re: Find what characters never appear

Just a chance this might work:

my %chars;
@chars{0 .. 127}=undef;
while(<>)
{
   for (split //)
   {
      delete $chars{ord $_} ;
   }
}

print "Chars never seen:\n";
$,="\n";
print keys %chars;
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You'd have to do some logic to filter out unprintables and to show the actual characters, rather than their decimal ASCII value

print pack("A25",pack("V*",map{1919242272+$_}(34481450,-49737472,6228,0,-285028276,6979,-1380265972)))

Comment on Re: Find what characters never appear Select or Download Code

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Re^2: Find what characters never appear by Narveson (Chaplain) on Sep 04, 2009 at 22:08 UTC
This ought to work. I appreciate the elegance of using the hash keys to keep track of a set, without ever updating any hash values (since after all it's only the keys that we need). The solution I actually ran was kennethk's above, which took over an hour. I suspect this one would take about as long, because even though it doesn't update any counts, it still reads every single character in the file. Thanks, your solution is running against my file right now. Launched it right about 22:00 GMT. I estimate it will finish in just under an hour.	[reply]

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Re^2: Find what characters never appear
by Narveson (Chaplain) on Sep 04, 2009 at 22:08 UTC

This ought to work. I appreciate the elegance of using the hash keys to keep track of a set, without ever updating any hash values (since after all it's only the keys that we need).

The solution I actually ran was kennethk's above, which took over an hour. I suspect this one would take about as long, because even though it doesn't update any counts, it still reads every single character in the file.

Thanks, your solution is running against my file right now.

Launched it right about 22:00 GMT. I estimate it will finish in just under an hour.

[reply]