Coalesce Operator

The coalesce operator ?? returns its first operand if it is set and not NULL. Otherwise it will return its second operand.

<?php

class x { }

// instantiation
$x = new x;

// cloning
$y = clone $x;

?>

Documentation

See also Null Coalescing Operator (??), PHP ternary operator vs null coalescing operator

Related : Ternary Operator, Colon, If Then Else, Short Ternary Operator

Added in PHP 7.0+