Hi all, let's say if

    text1:
    apple
    orange

    text2:
    apple
    apple
[download]

I try to delete the keys which are common in both text (only match once) and print out the mismatch. Apple of line 1 from text 1 and apple of line 1 from text 2 match, therefore deleted. But somehow apples of both lines in text 2 were deleted. Is there any better ways to delete just once for each existed data? After all of your generous help and tips,here is the code I have written. Cheers.

 
use strict;
use warnings;

open (FILE, "a") or die "Unable to open ref file.\n";
chomp (my @data1 =<FILE>) ;
close(FILE);

open (FILE, "b") or die "Unable to open new file.\n";
chomp (my @data2 =<FILE> );
close(FILE);
my $size = @data1 < @data2 ? @data1 : @data2; 
my $result= @data1 < @data2 ? "File 1 has missing data" : "File 2 has 
+missing data";
my $ori = @data1 == @data2 ? 1:0;
my $i;
for( $i = 0; $i < $size; $i++){
       if ($data1[$i] ne $data2[$i]){
        printf "%s is mismatch with %s\n",$data1[$i],$data2[$i];
       }
    else {
    printf "%s is match with %s \n",$data1[$i],$data2[$i];
    }

}
print "$result\n" if (!$ori);
[download]

Output:

apple is match with apple 
File 2 has missing data
[download]

Another method I have tried by comparing the arrays one by one. But there is a tricky part. What if Text 1 has one line while Text 2 has two lines?