php 21 3d operator

1$a == $b	Equal	TRUE if $a is equal to $b after type juggling.
2$a === $b	Identical	TRUE if $a is equal to $b, and they are of the same type.
3$a != $b	Not equal	TRUE if $a is not equal to $b after type juggling.
4$a <> $b	Not equal	TRUE if $a is not equal to $b after type juggling.
5$a !== $b	Not identical	TRUE if $a is not equal to $b, or they are not of the same type.
6$a < $b	Less than	TRUE if $a is strictly less than $b.
7$a > $b	Greater than	TRUE if $a is strictly greater than $b.
8$a <= $b	Less than or equal to	TRUE if $a is less than or equal to $b.
9$a >= $b	Greater than or equal to	TRUE if $a is greater than or equal to $b.
10$a <=> $b	Spaceship	An integer less than, equal to, or greater than zero when $a is less than, equal to, or greater than $b, respectively. Available as of PHP 7.

1$x = expr1 ?? expr2	Null coalescing return expr1 if not null or available 

1<?php
2var_dump(null ?? '`null` is null'); // `null` is null
3var_dump(null ?: '`null` is empty'); // null
4var_dump(true ?? '`true` is null'); // true
5var_dump(true ?: '`true` is empty'); // true
6var_dump(false ?? '`false` is null'); // false
7var_dump(false ?: '`false` is empty'); // `false` is empty"
8var_dump('' ?? 'empty string is null'); // ""
9var_dump('' ?: 'empty string is empty'); // "empty string is empty"
10var_dump(empty(null) ?: '`null` is not empty'); // true

1// Example usage for: Ternary Operator
2$action = $_POST['action'] ?: 'default';
3
4// The above is identical to this if/else statement
5if (empty($_POST['action'])) {
6    $action = 'default';
7} else {
8    $action = $_POST['action'];
9}