Print from array element to another array element

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

Hi all

I have a word split up by letters into a array. Let's say my word is "catfood", so then 'c' would be $array[0], and 'd' would be $array[6]

I want to print the word 'food' from my array

I tried this-

my $end = $#array;
print "$array[3..$end]\n";
[download]

and this

my $end = $#array;
print "$array[3]..$array[$end]\n";
[download]

but it doesn't work. Any help would be appreciated!

Comment on Print from array element to another array element Select or Download Code

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Re: Print from array element to another array element by kcott (Archbishop) on Apr 07, 2013 at 09:34 UTC
G'day Dr Manhattan, What you're attempting to use here are called Array Slices. They take the form: `@array_name[<list of indices>]`. See perldata - Slices. Your code should look something like this: `$ perl -Mstrict -Mwarnings -E ' my $word = q{catfood}; my @array = split // => $word; say join q{} => @array[3 .. $#array]; ' food` [download] -- Ken	[reply] [d/l] [select]
Re: Print from array element to another array element by Loops (Curate) on Apr 07, 2013 at 09:35 UTC
`use feature 'say'; my @array = split //, 'catfood'; say @array[3..$#array];` [download]	[reply] [d/l]
Re^2: Print/Lookup from array element to another array element by Dr Manhattan (Beadle) on Apr 07, 2013 at 09:53 UTC
Hi Loops I used the 'say' feature and it works correctly. My next question is- How do I lookup from one element in a array to another one? For instance the word "food" is a element in a hash. I want to lookup and if the combined elements of my array exists in the hash it should be printed I tried this- `if (exists $hash{@array[3..$end]}) { say @array[3..$end]; }` [download]	[reply] [d/l]
Re^3: Print/Lookup from array element to another array element by choroba (Cardinal) on Apr 07, 2013 at 09:59 UTC
The keys in a hash are always strings. You cannot use an array slice as a hash key. You have to join the list to form a string: `exists $hash{ join q(), @array[3 .. $end] }` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^3: Print/Lookup from array element to another array element by RichardK (Parson) on Apr 07, 2013 at 11:53 UTC
If you want to find one string inside another, just use index So, something along these lines :- `my $text ='catfood'; # returns -1 if not found say index($text,'food',0);` [download]	[reply] [d/l]
Re^3: Print/Lookup from array element to another array element by Anonymous Monk on Apr 07, 2013 at 10:02 UTC
You're skipping the basics, read perlintro, see perlfaq4 and Modern Perl	[reply]
Re: Print from array element to another array element by choroba (Cardinal) on Apr 07, 2013 at 10:02 UTC
The problem is that the range operator `..` is not recognised in double quotes. This should work, though: `print @array[3 .. $end], "\n";` [download] It might be faster and easier, though, not to split the string at all and work with substr and length. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re: Print from array element to another array element by BillKSmith (Monsignor) on Apr 08, 2013 at 02:56 UTC
You are attempting to write C, not perl. In perl, the word 'catfood' is a string, not an array. We use built-in functions and regular expressions for processing strings. It is possible to split a string into an array of characters, but reference still cannot be mamnipulated like a C pointer. Bill	[reply]
Re: Print from array element to another array element by reaper9187 (Scribe) on Apr 08, 2013 at 05:58 UTC
The easiest way to do it would be to use substr `use strict; use warnings; my $string = "catfood"; $string = substr($string,3,4); print "$string\n";` [download] You could also work on a copy of the original string by assigning the value to a separate string say : `my $new_string = substr($string,3,4);` [download]	[reply] [d/l] [select]