[Resolved] Getting odd and even values from a list

Seona

Hi guys,

I have a comma delimited list such as:

1,10,1,11,3,6

What I would like to do is get two lists as follows:

1,1,3
10,11,6

So, isolating the first, third, fifth, etc value and one isolating every second value. The list will be of variable length, but will always contain pairs of numbers.

Is there a function to do this? I can't find one in the php.net manual that makes sense in this context, but that doesn't mean it's not there. 🙂

Cheers,

Seona.

mtmosier

You could split it into an array using explode then check each one to see if its odd or even using the modulus operator.

Seona

Ah, no, I was afraid someone would get the wrong idea of what I was trying to do. I hoped I'd explained it adequetly, but apparently not.

I don't want to sort them based on whether the number is odd or even. I want to sort them into two lists:

List 1: first value, third value, fifth value...
List 2: second value, fourth value, sixth value...

Using the modulus operator will just tell me whether the value itself is odd or even, which is irrelevant to me. It's the placing that matters.

Unless there's some way of applying modulus to this that I'm unaware of?

mtmosier

Sorry, don't know where I got the odd / even thing from.

But then its just explode into an array and loop through. There's really not much to it beyond that. I mean you could make it more interesting and use regular expressions, but honestly that won't save you anything in complexity or lines of code, so no point.

mtmosier

Heh... I'm bored, so here's some code. Don't tell anyone I gave it to you though.

$list_orig = '1,10,1,11,3,6';
$numbers = explode(',', $list_orig);
$number_count = count($numbers);

$first = true;
$list1 = '';
$list2 = '';
for ($i = 0; $i < $number_count; $i += 2) {
    if ($i + 1 == $number_count) {
        echo 'Uneven number of items in list.';
        break;
    }

if (!$first) {
    $list1 .= ',';
    $list2 .= ',';
} else {
    $first = false;
}
$list1 .= $numbers[$i];
$list2 .= $numbers[$i + 1];
}

echo $list1."\n";
echo $list2."\n";

Seona

You should get bored more often. That does exactly what I need. Thanks. 🙂