需求：取文件1中的一行，和文件2中所有的数据进行比较，有相同的保存起来，否则删除。
#!/usr/bin/perl
#use strict;
open(FILE1,"C:/Perl/BX/BX-Users.txt");
open(FILE2,"C:/Perl/BX/BX-Book-Ratings.txt");
open(result1,">C:/perl/BX/BX-Users_result.txt");
my $i=0;
my $j=0;
while((my $bxUser=<FILE1>)&&($i<10))
{
my $userId=substr($bxUser,0,index($bxUser,","));
while(my $rankUser=<FILE2>)
{
my $userIdCmp=substr($rankUser,0,index($rankUser,","));
if(($userId==$userIdCmp)&&($j==0))
{
syswrite(result1,"$bxUser");
$j++;
}
}
$j=0;
$i++;
}
close(FILE1);
close(FILE2);
close(result1);