Building increasingly long strings from an array

Question

I am writing a PHP function that will take an array in the following format:

array(
    'one',
    'two',
    'three'
)

And echo the following strings:

one
one-two
one-two-three

I can't figure out how to do this. I've tried using a variable to store the previous one and then use it, but it only works for one:

$previous = null;
for($i = 0; $i < count($list); $i++) {
    echo ($previous != null ? $route[$previous] . "-" : '') . $route[$i];
    $previous = $i;
}

Outputting:

one
two
two-three

That approach would probably be inefficient anyway, as this script should technically be able to handle any length of array.

Can anybody help?

Answer 1

for ($i = 1, $length = count($array); $i <= $length; $i++) {
    echo join('-', array_slice($array, 0, $i)), PHP_EOL;
}