Re: comparing two files for duplicate entries

[Melly]

I don't know how well it would scale, but I'd build a hash from the first file ($objects{'object1'}=23.12;), then scan the second file. If the object in the second file has a defined hash, then print out the hashkey and both values..

Untested code... and I'm assuming a space delim. as per your examples..

open(FILE, "file1");
while(<FILE>){
  if(/(\S+)\s+(\S+)/){
    $hash{$1} = $2;
  }
}
close FILE;
open(FILE, "file2");
while(<FILE>){
  if(/(\S+)\s+(\S+)/){
    print "$1: $hash{$1} $2\n" if defined $hash{$1};
  }
}

[Fletch]

Yup, it's really just that simple (well, maybe exists rather than defined; but that's a minor nit). If your files are really, really big you probably want to use something like Berkeley_DB or one of the other DBM modules rather than reading everything into memory, but that's just an implementation detail; the basic algorithm remains the same.

[mk.]

or, just slightly different:

open(FILE1, "file1");
open(FILE2, "file2");
while(<FILE1>){
    /(\S*)\s+(\S*)/;
    $hash{$1}=$2;
}
while(<FILE2>){
    /(\S*)\s+(\S*)/;
    print "$1 $hash{$1} $2\n" if $hash{$1}
}