Convert a number to a string, the contents of which depend on the number's factors. #exercism
<?php
function raindrops($drops) {
$output = '';
if ($drops%3 == 0) {
$output .= "Pling";
}
if ($drops%5 == 0) {
$output .= "Plang";
}
if ($drops%7 == 0) {
$output .= "Plong";
}
return (empty($output) ? "$drops" : $output);
}