#!/usr/bin/perl #use strict; open(FILE1,"C:/Perl/BX/BX-Users.csv"); open(FILE2,"C:/Perl/BX/BX-Books.csv"); open(FILE3,"C:/Perl/BX/BX-Book-Ratings.csv"); open(result1,">C:/Perl/BX/BX-Users.txt"); my %table; my $record1; my $count1; #my $i=0; <FILE1>; while($_=<FILE1>) {     if($_ =~ /NULL$/){         next     }     else{     s/"//g;     my @list=split /;/,$_;     #print"@list";     push @{$table{$list[0]}},$list[2];     #print "$record1";     #$i++;     } } foreach my $userId(sort keys %table) {     my @AGE=@{$table{$userId}};     syswrite(result1,"$userId,@AGE");     $count1++; } print "$count1"; close(FILE1); close(result1); close(FILE2); close(FILE3);