A
B
C
####
1
5
10
##
##
A
BBBBB
CCCCCCCCCC
##
##
# Open both input files
open A, "<$file_a" or die "Unable to open $file_a: $!\n";
open B, "<$file_b" or die "Unable to open $file_b: $!\n";
# Process the files parallel
while (1) {
# Read the lines
my $a = ;
my $b = ;
# Good coders would check and warn if one entry was defined and the other
# was not, but this is just an example, so you should be happy you even
# get comments.
last if !defined $a || !defined $b;
# Process the output
print data_transform($a, $b);
}
close A;
close B;