(PECL ds >= 1.0.0)
Ds\Set::union — Creates a new set using values from the current instance and another set
Creates a new set that contains the values of the current instance as well as the
values of another set.
A ∪ B = {x: x ∈ A ∨ x ∈ B}
setThe other set, to combine with the current instance.
A new set containing all the values of the current instance as well as another set.
Example #1 Ds\Set::union() example
<?php
$a = new \Ds\Set([1, 2, 3]);
$b = new \Ds\Set([3, 4, 5]);
var_dump($a->union($b));
?>
以上例程的输出类似于：
object(Ds\Set)#3 (5) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
int(3)
[3]=>
int(4)
[4]=>
int(5)
}