# Define a hash for pk that have -C removed
my %hashC=();
.
.
sub input_data {
  my ($ix,$filename) = @_;
  open FILE1, "<", $filename or die "$filename : $!\n";
  while ( <FILE1> ) {
    chomp $_;
    my ( $key, $le, $date, $company ) = split ',', $_;    
    my $pk = join "\t",$key,$le,$company;

    # remove -C from key and store
    if ($pk =~ s/-C$//){
      # print "-C removed $pk\n";
      $hashC{$pk} = '-C';
    }
    
    push @{$hash{$pk}[$ix]},fmt_ymd($date);
  }
  close FILE1;
}

sub output_data {
  my $filename = shift;
  open OUTFILE, ">", $filename or die "$filename : $!\n";

  # primary key
  for my $pk (sort keys %hash){
    my ($key,$le,$company) = split "\t",$pk;
    # add -C back if required
    $company .= $hashC{$pk} || '';
.
.
.
[download]

ACFX 28523, L, 05/01/13, ABCCO-C
[download]

Thanks so much for the help again, I replace the sub input_data and sub output_data in original script with this and I get the following:

ACFX  28523  L           05/18/13  ABCCO    
ACFX  28523  L  05/01/13           ABCCO-C
[download]

I am pasting entire script, maybe I am doing something wrong, this is a little over my head, hopefully will begin understanding better

#!/usr/bin/perl
# 
use strict;
use warnings;
use Date::Calc qw( Delta_Days );

my %hashC=();
my %hash=();
input_data(1,'out1.txt');
input_data(2,'out2.txt');
#input_data(1,'pcarry.txt');
#input_data(2,'rcarry.txt');
output_data('final.txt');


#sub input_data {
#  my ($ix,$filename) = @_;
#  open FILE1, "<", $filename or die "$filename : $!\n";
#  while ( <FILE1> ) {
#    chomp $_;
#    my ( $key, $le, $date, $company ) = split ',', $_;
#    my $pk = join "\t",$key,$le,$company;
#    push @{$hash{$pk}[$ix]},fmt_ymd($date);
#  }
#  close FILE1;
#}
sub input_data {
  my ($ix,$filename) = @_;
  open FILE1, "<", $filename or die "$filename : $!\n";
  while ( <FILE1> ) {
    chomp $_;
    my ( $key, $le, $date, $company ) = split ',', $_;    
    my $pk = join "\t",$key,$le,$company;

    # remove -C from key and store
    if ($pk =~ s/-C$//){
    #  print "-C removed $pk\n";
      $hashC{$pk} = '-C';
    }
    
    push @{$hash{$pk}[$ix]},fmt_ymd($date);
  }
  close FILE1;
}

#sub output_data {
#  my $filename = shift;
#  open OUTFILE, ">", $filename or die "$filename : $!\n";

  # primary key
#  for my $pk (sort keys %hash){
#     my ($key,$le,$company) = split "\t",$pk;

sub output_data {
  my $filename = shift;
  open OUTFILE, ">", $filename or die "$filename : $!\n";

  # primary key
  for my $pk (sort keys %hash){
    my ($key,$le,$company) = split "\t",$pk;
    # add -C back if required
    $company .= $hashC{$pk} || '';


    # get multiple dates
#    print "$pk\n";
#   my @dates  = @{$hash{$pk}[1]};
#    my @rdates = @{$hash{$pk}[2]};
    my @dates  = (defined $hash{$pk}[1]) ? @{$hash{$pk}[1]} : ();
    my @rdates = (defined $hash{$pk}[2]) ? @{$hash{$pk}[2]} : ();
    
    # even up number of dates:
    while (@dates < @rdates) {
      push @dates,'1900-01-01';
    }
    while (@rdates < @dates) {
      push @rdates,'1900-01-01';
    }
    
    # print out multiple dates for each key
    for my $date (reverse sort @dates){
    
      # use match sub if more than 1
      if (@rdates > 1){
          @rdates = match($date,@rdates);
      }
      # rdates sorted so best match is first element
      my $rdate = shift @rdates;
      print join ' ',$key,$le,fmt_mdy($date),fmt_mdy($rdate),$company,
+"\n";
    }
  }
  close OUTFILE;
}

# match dates by calc days diff
# and sorting to get least diff
sub match {
  my ($date,@rdates) = @_;
  my @days=();
  # split date into y,m,d
  my @d1 = split /\D/,$date;
  
  # calc diff and store with date
  for my $rdate (@rdates){
    my @d2 = split /\D/,$rdate;
    push @days,[$rdate,abs Delta_Days(@d1,@d2)];
  }
  
  # sort array by days
  @days = sort {$a->[1] <=> $b->[1]} @days;
  
  # extract dates 
  return map {$_->[0]} @days;
}


# change mm/dd/yy to yyyy-mm-dd
sub fmt_ymd {
  my $mdy = shift;
  $mdy =~ s/ //g;
  my ($m,$d,$y) = split /\D/,$mdy;
  if ($y < 99){ $y += 2000 };
  return sprintf "%04d-%02d-%02d",$y,$m,$d;
}

# change yyyy-mm-dd to mm/dd/yy
sub fmt_mdy {
  my $ymd = shift;
  $ymd =~ s/ //g;
  return ' 'x8 if $ymd eq '1900-01-01';
  my ($y,$m,$d) = split /\D/,$ymd;
  $y -= 2000;
  return sprintf "%02d/%02d/%02d",$m,$d, $y;
}
[download]

I suggest you comment out this line temporarily
$company .= $hashC{$pk} || '';.

If you still get -C appearing in the output then check the data carefully for trailing spaces. You can also add the primary key into the output temporarily with separators like this to see spaces or other reason why they don't match up.

 print join ' ',$key,$le,fmt_mdy($date),fmt_mdy($rdate),$company,"|$pk
+|\n";
[download]

poj

In the example of what you need the output to look like, the carryover data is prepended to file 1. Carryover data, then file 1 data added to it.

I did figure out the formatting issue appending from carryover file to file1. So that seems to have helped some. I still do not match up because merging of the two files requires the company name be identical - however I must know which records were from the carryover file in the final output...any help is appreciated, thanks