Hmmm, Muthu... I fail to see how you can solve the problem described with the simple array comparison you suggest. It seems clear to me that any solution needs to focus on the first, 'key' field.
How else can one decided whether a a new record appeared in the same place where an old record was deleted?
Anyway...
For a large file, it probably needs to be pre-sorted and two two files read simultaneously comparing key values to keep then in sync.
I presented one example of this is in:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=999120For small files you can just 'slurp' them into a perl associative array, and report based on keys.
Here is an example that only compares the first non-field. It is easily adapted to compare other fields, or just everything except the key.
------ compare.pl ---------
$file = shift;
open (FILE, "<$file") or die "Failed to open first file: $file.";
while (
) {
chomp;
($key,$flag,$num) = split (/\|/, $_);
print "$. $key,$flag,$num\n";
$f1_flag{$key} = $flag;
$f1_num{$key} = $num;
}
$file = shift;
open (FILE, "<$file") or die "Failed to open second file: $file.";
while () {
chomp;
($key,$flag,$num) = split (/\|/, $_);
print "$. $key,$flag,$num\n";
$f2_flag{$key} = $flag;
$f2_num{$key} = $num;
}
for $key (sort keys %f2_flag) {
$change = "=";
if (defined $f1_flag{$key}) {
$change = "c" if ($f1_flag{$key} ne $f2_flag{$key});
delete $f1_flag{$key};
} else {
$change = "a";
}
print "$key|$f2_flag{$key}|$f2_num{$key}| $change\n"
}
for $key (sort keys %f1_flag) {
print "$key|$f1_flag{$key}|$f1_num{$key}| d\n"
}
---- usage example ----
C:\Temp>type file1.tmp
p1|y|500
p2|n|500
p5|y|500
C:\Temp>type file2.tmp
p1|n|500
p3|y|501
p5|y|500
C:\Temp>perl tmp.pl file1.tmp file2.tmp
p1|n|500 | c
p3|y|501 | a
p5|y|500 | =
p2|n|500 | d
if this input is treated as 'key' and everything else then it simplyfies some
------- compare_2.pl ----------
$file = shift;
open (FILE, "<$file") or die "Failed to open first file: $file.";
while () {
chomp;
$f1{$`} = $' if /\|/;
}
$file = shift;
open (FILE, "<$file") or die "Failed to open second file: $file.";
while () {
chomp;
$f2{$`} = $' if /\|/;
}
for $key (sort keys %f2) {
$change = "=";
if (defined $f1{$key}) {
$change = "c" if ($f1{$key} ne $f2{$key});
delete $f1{$key};
} else {
$change = "a";
}
print "$key|$f2{$key}| $change\n"
}
for $key (sort keys %f1) {
print "$key|$f1{$key}| d\n"
}
