What does "?:" mean in PHP?

Question

While browsing the code of an open source PHP library I spotted this line:

$path = $path ?: $this->guessPackagePath();

This is not the ternary operator like it usually apprears. Would anyone explain what is going on in it?

It's a ternary operator. http://www.php.net/manual/en/language.operators.comparison.php — Karl, Mar 26 '14 at 09:14
For completeness, this special kind of ternary is called [Elvis operator](http://en.wikipedia.org/wiki/Elvis_operator) — hanung, Mar 26 '14 at 09:29

xdazz · Accepted Answer · 2014-03-26T09:15:37.533

9

It's a shortcut for

$path = $path ? $path : $this->guessPackagePath();

which comes from PHP 5.3

edited Mar 26 '14 at 09:15

answered Mar 26 '14 at 09:10

xdazz

So what's going on in this unusual type of ternary op is that, if `$path` does not evaluate to `false` or an empty string, `$path` preserves its value, otherwise it's assigned to `$this->guessPackagePath()`, rite? – Desmond Hume Mar 26 '14 at 09:19
@DesmondHume Yes, that's right. – xdazz Mar 26 '14 at 09:22
Note that if `$path` is not yet set, that it will raise a PHP warning. – DanMan Jun 25 '14 at 15:03

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