$num = 5; $num++; echo $num; // Output: 6
$str = "Hello"; $str .= " World!"; echo $str; // Output: Hello World!
$arr = array(1, 2, 3); $arr[] = 4; print_r($arr); // Output: Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 )The self-addition operator is part of the PHP core language and does not require any external packages or libraries.