If your using 5.8, you could also use an "in memory file". See perlfunc:open pod from 5.8 for details, but basically this involves closing STDOUT and then re-opening it to a scalar ref.

close STDOUT;
open STDOUT, '>', \my $buffer or die $!;

print ....; # This will append the output to $buffer
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Alternatively, you could open another filehandle to a scalar and then select that filehandle as the default output stream prior to your print statements and select back when your ready to print output to STDOUT.