How to sort an array of strings numerically?

I feel like this is a simple problem. But I am stuck and to be honest my mind is having an info overload at the moment. I am also new to Perl and I’m still trying to explore it.

So I have a variable that contains a string:

$strings =
"3A
1B
2A
5A
4B"

then I converted it into an array by splitting it:

@split_array = split("\n", $strings);

print @split_array . "\n";

Output:

3A
1B
2A
5A
4B

Now, I want to sort this array in ascending order.

Here’s what I tried:

@sorted_array = sort @split_array;

Expected Output:

1B
2A
3A
4B
5A

but the output is still the same.

I apologize if I missed something obvious here.

Any help would be appreciated.

>Solution :

The split statement, split("", $strings); looks wrong – you are splitting on an empty string . I assume this is another typo?

This works fine for me

use strict;
use warnings;

my $strings = "3A 
100 
1B 
2A 
5A 
4B";

my @split_array = split(" ", $strings);

print "@split_array\n";

my @sorted_array = sort @split_array;
print "@sorted_array\n";

output is

3A 1B 2A 5A 4B
1B 2A 3A 4B 5A

Note that this is doing a string sort, rather than a numeric sort. It works in this instance because you are only sorting 2 character ASCII hex strings that happen to sort in proper numeric order. If the format is different, say the values contain 3 character ASCII hex, that string sort will not work properly.

For example

use strict;
use warnings;

my $strings = "3A 
100 
1B 
2A 
5A 
4B";

my @split_array = split(" ", $strings);

print "@split_array\n";

my @sorted_array = sort @split_array;

outputs

3A 100 1B 2A 5A 4B
100 1B 2A 3A 4B 5A

To fix that you need to do a proper numeric sort. That means converting the ASCII hex numbers into their binary equivalent.

use strict;
use warnings;

my $strings = "3A 
100 
1B 
2A 
5A 
4B";

my @split_array = split(" ", $strings);

print "@split_array\n";

my @sorted_array = sort @split_array;
print "@sorted_array\n";

my @numeric_sorted_array = sort { hex $a <=> hex $b } @split_array;
print "@numeric_sorted_array\n";

output is

3A 100 1B 2A 5A 4B
100 1B 2A 3A 4B 5A
1B 2A 3A 4B 5A 100

The key here is the sort { hex $a <=> hex $b } expression — this converts the ASCII hex into binary with the hex function, the uses the <=> operator to carry out a numeric sort.