是否可以使用null合并运算符执行此操作？

Question

With isset(), you can do this:

$foo = [];
$baz = [];
$bar = isset($foo['bar'], $baz[$foo['bar']]) ? $baz[$foo['bar']] : '';

Is it possible to achieve the same thing with null coalescing like:

$bar = ($foo[$bazz['foo']]) ?? ''; //Undefined variable: bazz

Im expecting $bar to be:

$bar = '';

??: Null coalescing operator

Answer 1

You have to use the ?? operator twice.

$foo = [];
$baz = [];
$bar = $baz[$foo['bar'] ?? ''] ?? '' ;

See it in action on 3v4l.org