Re^3: Simple comparison of 2 files

[Paladin]

Ok, that makes it clear. Your issue is with the line:

if ($FILE1letter == $FILE2letter) {

Use the eq operator to compare strings. == compares numerically.

[pryrt]

and the next issue is that you're only looping thru the second file once; to be able to compare every line of file1 against every line of file2, you're going to need to parse the second file multiple times (ie, nested loop); alternatively, grab all of file2 into an appropriate data structure, and compare each line of file1 to each entry in the file2 data structure (or vice versa, or both into data structures, then just compare the data)

update1

#!perl
open (FILE1, $ARGV[0]);

while ($_ = <FILE1>) {
    chomp;
    @FILE1 = split;
    ($FILE1letter, $FILE1number) = @FILE1;

    open (FILE2, $ARGV[1]);
    while( $two = <FILE2> ) {
        @FILE2 = split(' ',$two);
            ($FILE2letter, $FILE2number) = @FILE2;
            #   print "$FILE1letter from FILE1 with number $FILE1numbe
+r and $FILE2letter from FILE2 with $FILE2number match\n";
            #   prints the same as below

        if ($FILE1letter eq $FILE2letter) {
            print "$FILE1letter from FILE1 with number $FILE1number an
+d $FILE2letter from FILE2 with number $FILE2number match\n";
        } else {
            print "$FILE1letter from FILE1 with number $FILE1number an
+d $FILE2letter from FILE2 with number $FILE2number DO NOT match\n";
        }
    }
    close (FILE2);
}
__END__
C:\Temp>perl ab.pl a b
A from FILE1 with number 1_1 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_1 and B from FILE2 with number 2_2 DO NOT m
+atch
A from FILE1 with number 1_2 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_2 and B from FILE2 with number 2_2 DO NOT m
+atch
B from FILE1 with number 1_3 and A from FILE2 with number 2_1 DO NOT m
+atch
B from FILE1 with number 1_3 and B from FILE2 with number 2_2 match
C from FILE1 with number 1_4 and A from FILE2 with number 2_1 DO NOT m
+atch
C from FILE1 with number 1_4 and B from FILE2 with number 2_2 DO NOT m
+atch

[Q.and]

Excellent, this is exactly the issue I was dealing with- thank you!

[pryrt]

alternately, to avoid len(file1) x len(file2) loops,

use autodie;
use warnings;
use strict;
my (@data1, @data2) = ();
my ($fh, $l, $n);
open $fh, "<", $ARGV[0];
while(<$fh>) {
    ($l, $n) = split;
    push @data1, [ $l, $n ];
}
close($fh);
open $fh, "<", $ARGV[1];
while(<$fh>) {
    ($l, $n) = split;
    push @data2, [ $l, $n ];
}
close($fh);

foreach my $row1 ( @data1 ) {
    foreach my $row2 ( @data2 ) {
        my ($l1, $n1, $l2, $n2) = (@$row1, @$row2);
        my $match = $l1 eq $l2;
        print "$l1 from FILE1 with number $n1 and $l2 from FILE2 with 
+number $n2" . ($match ? '' : " DO NOT") . " match\n";
    }
}
__END__
A from FILE1 with number 1_1 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_1 and B from FILE2 with number 2_2 DO NOT m
+atch
A from FILE1 with number 1_2 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_2 and B from FILE2 with number 2_2 DO NOT m
+atch
B from FILE1 with number 1_3 and A from FILE2 with number 2_1 DO NOT m
+atch
B from FILE1 with number 1_3 and B from FILE2 with number 2_2 match
C from FILE1 with number 1_4 and A from FILE2 with number 2_1 DO NOT m
+atch
C from FILE1 with number 1_4 and B from FILE2 with number 2_2 DO NOT m
+atch

this will save a lot of time if the files are significantly larger than 4 and 2 lines, respectively. though it will end up using more memory...

[Q.and]

Oh man, super rookie mistake there- thanks for catching that. However, even when corrected, it prints:
A from FILE1 with number 1_1 and A from FILE2 with number 2_1 match
A from FILE1 with number 1_2 and B from FILE2 with number 2_2 DO NOT match
B from FILE1 with number 1_3 and from FILE2 with number DO NOT match
C from FILE1 with number 1_4 and from FILE2 with number DO NOT match

and is still is missing two of the matches and two of the mismatches, so that's in the looping.