php - Get the first and last word on an array

Use current() for first element and end() for last element

$text = "Barcelona, Catalunya, Spain";
$exp = explode(", ", $text);

$string = current($exp) . ", " . end($exp);

DEMO

If you want to get the first and last x elements, you can use array_slice() but as you want the gap, simply array_combine() two slices like this

function createCenteredGap($gapLength, $text) {
    $length = (strlen($text) - $gapLength) / 2;
    $gapLength = 1;
    return array_merge(
        array_slice($text, 0, $length),
        array_slice($text, $length+$gapLength, $length)
    );
}

This will do the trick when called like createCenteredGap(1, $text) as you can see in this demo

<?php
   $array = array(Barcelona, Catalunya, Spain);
   $first = reset($array);
   $last = end($array);

   var_dump($first, $last);
?>

Try to use this very simple regexp

preg_match('/^(.[^,]*)\s*,.*,\s*(.*)$/', $text, $match);
$first = $match[1];
$last = $match[2];

If you are sure that elements are only words without digits and other symbols you can modify this regexp

$text now has the array of values so

first element:

$text[0]

or

reset($text)

last element:

end($text)

Don't split your string at all. Use preg_replace() to capture all consecutive repetitions of a comma followed by non-comma characters and replace the lot with the last repetition. Demo

echo preg_replace('#(,[^,]+)+#', '$1', $text);
// Barcelona, Spain