What does $variable ?: [] do?

Question

$variable ?: []

What does it do? It's a ternary operator but looks a bit different and I don't know what [] means. Perhabs it's shorthand array of 5.4 and creates an empty array?

This code will throw an `E_NOTICE` if `$variable` is not set. So I would say it's better to test `if (!isset($variable)) { $variable = array(); }`. — insertusernamehere, Apr 19 '13 at 15:46
I would not say this is a dup. The dup question specifies `?` and `:`, this question is when `?:` are together with no if true. — Ryan B, Apr 19 '13 at 15:50

score 7 · Accepted Answer · answered Apr 19 '13 at 15:42

7

This is shorthand for:

if ($variable) {
    // nothing
} else {
    $variable = array();
}

[] is PHP 5.4 shorthand for array()

answered Apr 19 '13 at 15:42

Halcyon

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If you're going to expand it, wouldn't it make more sense as: `if(!$variable) $variable = array()`? – Niet the Dark Absol Apr 19 '13 at 15:43
That depends on how strict you want to expand it. I'll stick with my interpretation. – Halcyon Apr 19 '13 at 15:46

score 2 · Answer 2 · answered Apr 19 '13 at 15:43

It means:

If $variable has a value then use that value, otherwise use an empty array.

The [] syntax is PHP 5.4 shorthand syntax for an empty array.
PHP 5.3 and earlier would write it as array().

In other words, yep, your guess in the question about what it does is pretty much exactly right.

What does $variable ?: [] do?

2 Answers2

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