(PECL ds >= 1.0.0)
Ds\Set::diff — Creates a new set using values that aren't in another set
Creates a new set using values that aren't in another set.
A \ B = {x ∈ A | x ? B}
setSet containing the values to exclude.
A new set containing all values that were not in the other set.
Example #1 Ds\Set::diff() example
<?php
$a = new \Ds\Set([1, 2, 3]);
$b = new \Ds\Set([3, 4, 5]);
var_dump($a->diff($b));
?>
以上例程的输出类似于：
object(Ds\Set)#3 (2) {
[0]=>
int(1)
[1]=>
int(2)
}