Re^2: Interpolation in a hash key

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Re^3: Interpolation in a hash key by pickledegg (Novice) on Jun 13, 2006 at 15:58 UTC
Sorry chaps, I don't follow what you are doing there at all. I'm quite a novice. If I have: `$$hashRecordPtr{'connection1_size1'}` if I set $count to 3 how can I replace the size1 for size$count and get $$hashRecordPtr{'connection1_size3'} ? Do you see what I'm getting at? I know you do as you are way above me in the perl stakes, I just don't understand your answer, sorry.	[reply] [d/l]
Re^4: Interpolation in a hash key by davorg (Chancellor) on Jun 13, 2006 at 16:06 UTC
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	[reply] [d/l] [select]
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]