Perl array access in a for loop

arun10427 has asked for the wisdom of the Perl Monks concerning the following question:

I am a perl newbie. I am using a perl code to read a column full of data from 1 field into an array

for(my $i=2;$i<table->last_record;$i++)
my @data = $table->get_record($i,"Date");
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Now for example if my @data[1] consists of list of numbers, I need to find the diff between current record and prev record till it reaches the end of array.. Perl has such complex way of array accessing, I donno how to do $data[$i]-$data[$i-1].

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Re: Perl array access in a for loop by GrandFather (Saint) on Oct 24, 2009 at 20:11 UTC
Actually it's just: `$data[$i] - $data[$i - 1]` [download] What though have you actually tried? What error message or behaviour is confusing you? Can you put together a sample something like the following code that demonstrates the problem you have? `use strict; use warnings; my @table = (1, 2, 4, 6, 10); my @diffs; for my $index (0 .. $#table - 1) { $diffs[$index] = $table[$index + 1] - $table[$index]; } print "@diffs\n";` [download] True laziness is hard work	[reply] [d/l] [select]

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Re: Perl array access in a for loop
by GrandFather (Saint) on Oct 24, 2009 at 20:11 UTC

Actually it's just:

$data[$i] - $data[$i - 1]
[download]

What though have you actually tried? What error message or behaviour is confusing you? Can you put together a sample something like the following code that demonstrates the problem you have?

use strict;
use warnings;

my @table = (1, 2, 4, 6, 10);
my @diffs;

for my $index (0 .. $#table - 1) {
    $diffs[$index] = $table[$index + 1] - $table[$index];
}

print "@diffs\n";
[download]

True laziness is hard work

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