note
vroom
<code>
# Reads in lines of text until "quit" is read.
# Then prints duplicates, or prints "No duplicates seen."
my %lines; # holds lines of text encountered along with a count
# of how many times it has been seen
my @dups;
while ( $_ = <> and $_ ne "quit\n" )
{
$lines{$_}++; # increment value. if it dosn't exist yet, initializes to 1
if ( $lines{$_} == 2 ) # been seen before so add to dupes list
{
push @dups, $_;
}
}
if ( @dups )
{
print "Here are your duplicate lines:\n\n";
foreach ( @dupes )
{
print;
}
}
else
{
print "No duplicates seen.\n";
}
</code>
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