#!/bin/perl
use strict; 
use warnings; 
my $filename; 
my %hash; 
my @information; 
my $key1; 
my $key2; 
print "please put in the file like this f:\\\\perl\\\\data.txt\n"; 
chomp($filename=STDIN>); 
open(IN,"$filename")||die("can not open"); 
while(IN>) 
{ 
   chomp; 
   @information=split/\s+/,$_; 
   if(exists $hash{$information[0]}{$information[1]}) 
   { 
       next; 
   } 
   else 
   { 
       $hash{$information[0]}{$information[1]}='A'; 
    } 
   } 
   close IN; 
   open(IN,"$filename")||die("can not open"); 
   while(IN>) 
   { 
       @information=split/\s+/,$_; 
       if(exists $hash{$information[1]}{$information[0]}) 
       { 
           delete $hash{$information[0]}{$information[1]} 
       } 
       else 
       { 
           next; 
       } 
   } 
   close IN; 
   open(OUT,">f:\\A_B_result.txt")||die("can not open"); 
   foreach $key1 (sort{$a=>$b} keys %hash) 
   { 
       foreach $key2 (sort{$a=>$b} keys %{$hash{$key1}}) 
       { 
           print OUT "$key1 $key2\n"; 
       } 
   } 
close OUT;

#!/usr/bin/perl
# Author :CaoJiangfeng
# Date:2011-09-28
# Version :1.0
use warnings;
use strict;

my %hash;
my $script = $0; # Get the script name

sub usage
{
        printf("Usage:\n");
        printf("perl $script source_file> dest_file>\n");

}

# If the number of parameters less than 2 ,exit the script
if ( $#ARGV+1 2) {

        usage;
        exit 0;
}

my $source_file = $ARGV[0]; #File need to remove duplicate rows
my $dest_file = $ARGV[1]; # File after remove duplicates rows

open (FILE,"$source_file") or die "Cannot open file $!\n";
open (SORTED,">$dest_file") or die "Cannot open file $!\n";

while(defined (my $line = FILE>))
{
        chomp($line);
        $hash{$line} += 1;
        # print "$line,$hash{$line}\n";
}

foreach my $k (keys %hash) {
        print SORTED "$k,$hash{$k}\n";#改行打印出列和该列出现的次数到目标文件
}
close (FILE);
close (SORTED);

#!/usr/bin/perl
use strict;
my %hash;
my @array = (1..10,5,20,2,3,4,5,5);
#grep 保存符合条件的元素
@array = grep { ++$hash{$_} 2 } @array;
print join(" ",@array);
print "\n";