<?php

$string = "|1|2|3|4|";
$string = substr($string,1,-1);
$array = explode("|", $string); 

foreach ($array as $part) {
    echo $part."-";
}
echo PHP_EOL ;

/* or use implode to joib */
echo implode("-",$array);

?>

1-2-3-4-
1-2-3-4