for each line in File1,
    look at each line in File2
    and for each of the fields in the current line
        if the field has the same stuff in it as the corresponding fie
+ld in the current line of File 2 -
            remember it,
        otherwise -
            fuggedaboudit
print out a report of all the stuff I remembered
[download]

foreach (line in File1) {
    look at each line in File2;
    foreach (field in the current line) {
        if (the field has the same stuff in it as the corresponding fi
+eld in the current line of File 2) {
            remember it;
        }
        else {
            fuggedaboudit;
        }
    }
}
print out a report of all the stuff I remembered;
[download]

my @files = ('File1','File2');
my $file;
foreach $file (@files) {
    do stuff with $file ...
[download]

foreach $file (File1..File2) {
    do stuff with $file ...
[download]

for (File1..File2) {
    do stuff with $_ ...
[download]

To everyone who replied to my post, thankyou. Particularly to George, many thanks, as it was your thoughts that enabled me to solve this one. I'm pretty chuffed with the code I did, even though for most of you this will be very basic and easy perl. Nevertheless, in case anyone can use it, here it is. Of course, if anyone wants to offer improvements on it, please feel free...

#!/usr/bin/perl

print "Content-type: text/html\n\n";
$file1 = "file1.txt";
$file2 = "file2.txt";
open(FILE1,"<$file1"); 
@file1 = <FILE1>;
close(FILE1);
open(FILE2,"<$file2"); 
@file2 = <FILE2>;
close(FILE2);

$matches = 0;    
foreach $line ( @file1 ) {    
    foreach $line2 ( @file2 ) {    
    @array1 = split (/\|/, $line);    
    @array2 = split (/\|/, $line2);    
    $numavail = @array1;
    $limit = $numavail - 3;    
        for ( $i=12; $i < $limit; $i++ )  {         
            if ( $array1[$i] eq $array2[$i] ) {    
            $matches++;    
                   }    
            }    
        if ( $matches >= 1 && $array1[14] ge $array2[14] && $array1[12
+] le $array2[12]) {            

print "Here is where I print the data I want to retreive, using things
+ like $array1[12] etc";
        }            
    $matches = 0;        
    }            
}
[download]

OK, this doesn't sound so difficult ... if possible I would read file2 completely into memory, already split up into a 2D array. So $file2[0][1], e.g. would be the 2nd field in line 1 of file2.

Having done that, proceed along the lines of the following (pseudo-)code:

# process file1 line by line
while ($line = <FILE1>) {

  # split up the current line in file1
  @fields = split /!/, $line;

  # for each line in the 2nd file
  foreach $lineref (@file2) {
    $number_of_matches = 0;

    # compare the two lines
    for $index (0..$number_of_fields) {
      $number_of_matches++
       if ($lineref->[$index] eq $fields[$index]);
    }
    print "Matchinfo: ...";
  }
}
[download]

-- Hofmator

What do you mean by matches? Do you mean a field in line 1 of file 1 happened to be the same as a field in line 2 of file 2? Does it matter if the match is between field 1 and field 5, or do the fields in question have to match up?

Without being able to state a clear spec, it is hard to meet it.

Anyways, some tips.

1. However you solve the problem, it will probably help to have nested data structures. And for that it will help to read through References quick reference.
2. To see if an actual data structure looks like you wanted it to look like, you can try Data::Dumper.
3. Any problems of the form "This matches something in that list" are usually best handled in Perl by taking that list, and turning it into a hash, then doing a hash lookup.
4. Take things one step at a time. If the full problem is too much for you, just find a piece you can handle. For instance figure out what internal data structure you want to use, and then inline some sample data in your script and try to work with that. Once you can get an answer from the parsed data, then worry about building a piece that reads the file into that structure...

One way of approaching a problem of this kind is to find an effective way to represent the data. First, I'll assume your files are small enough to hold in memory. Putting files into an array of arrays:

my $ifs = '|'; # or whatever

open FH, "<$file1path" or die $1;
my @file1data = map {[split $ifs, $_]} <FH>;
close(FH( or die $!;

open FH, "<$file2path" or die $1;
my @file2data = map {[split $ifs, $_]} <FH>;
close(FH) or die $!;
[download]

my $lastrec = scalar( @{$file1data[0]}) - 1;

my @scores = map {
    my $d1 = $_;         # arrayref of a record from file11
    [ map {              # an arrayref with score for each record from
+ file2
        my $d2 = $_;     # arrayref of a record from file12
        scalar grep {    # count stringy matches 
            $d1->[$_] eq $d2->[$_];
        } 0..$lastrec;
    } @file2data ];
} @file1data;
[download]

After Compline,
Zaxo