Mastering PHP 7

The null coalesce operator

Working with variables in PHP is quite easy. Variable declaration and initialization is done via a single expression. For example, the expression $user['name'] = 'John'; will automatically declare variable $user of type array and initialize that array with a single key name of value John.

Day-to-day development often includes checking for the existence of a variable value for various branching decisions, such as if ($user['name'] =='John') { … } else { … }. As we write our code ourselves, we tend to make sure that our code does not use non-declared variables and non-initialized array keys. There are cases, however, where variables come from outside, so we are not really in a position to guarantee their existence ...