_{Official ZPE/YASS documentation}Alternative values

Alternative values are a powerful way of safely setting a value without relying on the built-in is_set function. Alternative values were added in ZPE version 1.7.11 (September 2019).

An alternative value is a syntax that allows the programmer to define a fall back value in the case that a value is undefined or null.

The alternative value is specified with the ?? syntax after an expression:

⟨expression1⟩ ?? ⟨expression2⟩

For example:

$search = input("Please insert the username you are looking for.")
$users = ["jamie1" => "Jamie Balfour", "john1" => "John Balfour"]

print($users[$search] ?? "User not found")
    

If the user were to input a username that does not exist in the array, the print method would not print undefined but would instead print User not found because of the ?? specifying an alternative value.