Plus +¶

+ is a native PHP operator, which has three usages:

The addition, as in mathematics, on numbers. This works on integers and floats.
The merging of arrays. This merge sets the keys once, then omits the next values. This is distinct from array_merge().
The + sign in front of a number, to make it explicitly positive. This is optional, and may be repeated.

<?php

    $a = 1 + 2; // 3

    $b = [1, 2] + [3, 4, 5]; // [1,2, 5]

    $c = +6; // 6

?>