Re: can i concatenate various value to form a unique key

It is completely fine to make a hash key from other strings. like:

#!/usr/bin/perl -w
use strict;

my %hash;
$hash{'my_mother=Nice,my_brother=Great;3;45;987;'}='True';

foreach my $key (keys %hash)
{
   print "$key VALUE =$hash{$key}\n";
}
__END__
prints:
my_mother=Nice,my_brother=Great;3;45;987; VALUE =True
[download]

Update:
I would argue that this is not the best way:
my $key = join ("",$value1,$value2,$value3,$value4,$value5);
consider:
my $key ="$value1$value2$value3$value4$value5";
if say $value3 doesn't exist, then,
$key = "$value1$value2$value4$value5";
Oooops!...maybe a problem!!!

$hash{"$value1;$value2;$value3;$value4;$value5"} = 123;
is "better" (provided that ";" doesn't occur in the $values).
The reason for the ";" is so that there will always be a unique value even if one of the $value vars is ""!.

Comment on Re: can i concatenate various value to form a unique key Download Code

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Re^2: can i concatenate various value to form a unique key by Anonymous Monk on Jul 03, 2009 at 10:19 UTC
hoo so is it possible to have mutiple values as key whose combination will be unique? and I dont have to download any CPAN modules for the same also?	[reply]
Re^3: can i concatenate various value to form a unique key by Marshall (Canon) on Jul 03, 2009 at 12:19 UTC
The short answer is yes. A hash key can be any string as long as that string is unique. The "classic example" is printing a file and omitting duplicate lines that have been seen before.... `#!usr/bin/perl -w use strict; my %seen; while (<DATA>) { print unless $seen{$_}++; } #Prints: #1 2 this is a line with 1 and 2 #3 a line with just 3 #5,6 five before 6 #5,6 five before six (different) #6,5 #blah __DATA__ 1 2 this is a line with 1 and 2 3 a line with just 3 1 2 this is a line with 1 and 2 3 a line with just 3 5,6 five before 6 5,6 five before six (different) 6,5 blah blah` [download] In general, I would not concatenate keys together. Well, until you have learned multi-dimensional structs, I would say that concatenating 2 things and not more is "ok". There are some advanced techniques where say 8 dimensions can be combined into a single hash key, but those situations are seldom and not applicable for normal code (a way to describe state tables and a way to simplify horrifically complex logic statements).	[reply] [d/l]