Re^4: Interpolation in a hash key

Ok. Let's get back to basics then :)

When you look things up in a hash, you use a string as the index. So your first example is the same as:

$index = 'connection1_size1';
$$hashRecordPtr{$index};
[download]

Do you follow that? The hash index is just any string value.

But what we've done there is to now use a variable as the hash index. Which means that we can now be a bit cleverer.

$index = "connection1_size$count";
$$hashRecordPtr{$index};
[download]

So now we have a double-quoted string, and we've used the value of the variable $count within the string.

So that effectively does what you want, but we can cut out the unnecessary $index variable and use the double-quoted string directly as the hash index.

$$hashRecordPtr{"connection1_size$count"};
[download]

Is that any clearer?

--
<http://dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

Comment on Re^4: Interpolation in a hash key Select or Download Code

Replies are listed 'Best First'.
Re^5: Interpolation in a hash key by ptum (Priest) on Jun 13, 2006 at 16:18 UTC
... and of course, there are some times when we need to help the interpreter know when our variable begins and ends. In the example davorg gave you, $count fell at the end of your hash key (index). But suppose you wanted the $count to fall in the middle of your key, like this: `$index = "connection$countsize";` [download] How would the interpreter know that you were referring to $count? You might have also been referring to $counts, $countsi, $countsiz, or $countsize. In such cases, you would put curly braces around the variable name to delimit it from the rest of the text. `$index = "connection${count}size";` [download] No good deed goes unpunished. -- (attributed to) Oscar Wilde	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^5: Interpolation in a hash key
by ptum (Priest) on Jun 13, 2006 at 16:18 UTC

... and of course, there are some times when we need to help the interpreter know when our variable begins and ends. In the example davorg gave you, $count fell at the end of your hash key (index). But suppose you wanted the $count to fall in the middle of your key, like this:

$index = "connection$countsize";
[download]

How would the interpreter know that you were referring to $count? You might have also been referring to $counts, $countsi, $countsiz, or $countsize. In such cases, you would put curly braces around the variable name to delimit it from the rest of the text.

$index = "connection${count}size";
[download]

No good deed goes unpunished. -- (attributed to) Oscar Wilde

[reply]
[d/l]
[select]