-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Are you saying I should just write to a flatfile if all I'm trying to save is a single variable?

Yes, that's exactly what merlyn is trying to get across. A database is pretty useless if you are only storing a single value. Much easier to simply manage a flat file and be able to read it into an array. A database becomes useful when you need to associate one piece of data with another.

For your example, you are not associating anything with the name. All you have is a name. No age, email adress, phone number, or anything related to the user. If you did have anything, you'd then be using something like this:

# I've never really used a dbm.
# They allow complicated structures, right?
$dbm{$name}{'age'}   = 29;
$dbm{$name}{'email'} = 'nobody@example.com';
[download]

For a single value, I'd probably use something like this. It could use a little more work :)

use Fcntl ':flock';

sub add_names {
 my @add = @_;

 open my $fh, '+<', 'names.dat';
 flock $fh, LOCK_EX;
 chomp( my @names = <$fh> );
 seek $fh, 0, 2;

 for my $name (@add) {
  warn "$name is already in file" and next
   if grep { /^$name$/i } @names;
  print $fh "$name\n";
 }

 close $fh;
}

sub get_names {
 open my $fh, '<', 'names.dat';
 chomp( my @names = <$fh> );
 close $fh;

 return @names;
}

sub del_names {
 my @del = @_;

 open my $fh, '+<', 'names.dat';
 flock $fh, LOCK_EX;
 chomp( my @names = <$fh> );
 truncate $fh, 0;
 seek $fh, 0, 0;

 for my $name (@names) {
  print $fh "$name\n" unless grep { /^$name$/i } @del;
 }
 close $fh;
}
[download]

---

If the above content is missing any vital points or you feel that any of the information is misleading, incorrect or irrelevant, please feel free to downvote the post. At the same time, please reply to this node or /msg me to inform me as to what is wrong with the post, so that I may update the node to the best of my ability.

$dbm{'name'} = $name overwrites the previes entry
$dbm{$name'} = $name creates redundant Aaron Aaron
$dbm{$name}; creates Useless use of DBM error
$dbm{$name} = ""; writes Aaron
[download]

$dbm{'name'} = $name overwrites the previes entry
# Yes, quite correct

$dbm{$name'} = $name creates redundant Aaron Aaron
# I don't think so. You've got bad punctuation there,
what do you expect Perl to do? Perhaps you're creating a
 value of "Aaron" but with a key of "Aaron'" -- see quotes?

$dbm{$name}; creates Useless use of DBM error
# quite so. Meaningless if that's the whole statement.

$dbm{$name} = ""; writes Aaron
# no it doesn't, I'm betting. $dbm{$name} should be an
 empty string now.
[download]

Prove it to us with some more code?

Like for instance:

$name = Aaron;
$dbm{$name} = $name;
print $dbm{$name};
$dbm{$name'} = $name;
print $dbm{$name'};
[download]

“Every bit of code is either naturally related to the problem at hand, or else it's an accidental side effect of the fact that you happened to solve the problem using a digital computer.”
M-J D

I will post my code at the bottom of this message. What I meant with $dbm{$name} = $name; was it would hold Aaron as the key and Aaron as the value so if I were to print out the database it would print Aaron Aaron.

The code that works for me is actually $dbm{$name} = "";, it's the only one that does what I want. You can test the script itself from what I posted below.

#!/usr/bin/perl -W

use strict;
use warnings;
use POSIX;
use CGI;

require SDBM_File;

my %dbm;
my $test = "test.dbm";

tie (%dbm, 'SDBM_File', $test, O_CREAT|O_RDWR, 0644)
   || die "Died tying database\nReason: $!\n";
   
print "Aaron's Phonebook System\n\n\n";

print "What is their name?\n";
my $name = $_;
#if ($name ne "") {
chomp($name = <STDIN>);
$dbm{$name} = "";

print "Added to the list!\n";
[download]



"Age is nothing more than an inaccurate number bestowed upon us at birth as just another means for others to judge and classify us"

sulfericacid

print "What is their name?\n";
my $name = $_;
#if ($name ne "") {
chomp($name = <STDIN>);
$dbm{$name} = "";
print "Added to the list!\n";
[download]

should read more like

print "What is their name?\n";
chomp($name = <STDIN>);
chomp($number = <STDIN>);
$dbm{$name} = $number;
print "$name = $dbm{$name} added to the list!\n";
[download]

shouldn't it?


---
demerphq

Honestly, I'm more confused than ever now that you've posted that code.
--


“Every bit of code is either naturally related to the problem at hand, or else it's an accidental side effect of the fact that you happened to solve the problem using a digital computer.”
M-J D