To add yet another answer to your question - the reason why this isn't working is that symbolic references can only be used for the name of a variable. You may think that in the second example, you have a variable called "a[3]" containing the string "Hello", but you don't; what you actually have is an array called "a", and an element in that array at index 3 containing that string.

Simply put, you cannot refer to individual array elements by way of a symbolic reference. That said, however, you can use a symbolic reference to the array itself, so the following works:

$a[3] = "Hello";

$b = "a";
$c = "3";

$d = $$b[$c];

print $d;
[download]

But again, this is generally a bad idea. In addition to what others have said, keep in mind that symbolic references can only refer to package variables, not lexicals (i.e. variables declared with my). As a result, symbolic references are by necessity forbidden when use strict is in effect.

And speaking of which, you should always use use strict; it'll catch many bugs for you.

Technically, it's possible to turn strict references off by saying no strict 'refs', without affecting the rest of what use strict does. Nonetheless, avoid using symbolic references. Perl gives you enough rope to hang yourself with, but doing so is still not a good idea.

Better read the link brother Choroba gave you and use this code instead.

$HoA{a}[3]=“hello";
print $HoA{a}[3];
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See perldsc for details about nested data.

HTH :)

update

symbolic refs don't seem work with nested data, the only way to make your code "work" is

 $d = eval "$b$c"

please note that you forgot the $ sigil in $b ='$a' ( or $b ="\$a" if you need double quotes)

Hello Krillian, and welcome to the Monastery!

In addition to the reference linked above by choroba, please read the FAQ How-can-I-use-a-variable-as-a-variable-name of perlfaq7.

Hope that helps,

There is nothing elegant, or smart about doing this, but because we're playing with Perl, it is possible:

$a[3] = "Hello";
$b = 'a';
$c = '[3]';
$d = eval "\$$b$c";
print "$d\n";
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Output: Hello. Hopefully the fact that this violates strict 'refs', strict 'vars', and requires string eval should be enough warning flags to dissuade using the construct.

Here's how it works. First, we assign a value to $a[3]. Then we construct a string that looks like "$a[3]" using a component that looks like "a", and a component that looks like [3]. Then we evaluate that string as if it were code. The code is an expression returning the value stored in @a's fourth element.

> this violates strict 'refs', strict 'vars',

To be precise: eval doesn't violate strict 'refs' and strict 'vars' is easily calmed with my declarations ( though the OP never used strict )...

> perl
use strict;
use warnings;

my @a;
$a[3] = "Hello";
my $b = 'a';
my $c = '[3]';
my $d = eval "\$$b$c";
print "$d\n";
__END__
Hello
[download]

Cheers Rolf

_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}