Which function is used to check if a variable is defined and not null?

Question

PHP Intermediate — Medium

Which function is used to check if a variable is defined and not null?

Accepted Answer

The `isset()` function determines if a variable is declared and is different than null. It returns false if the variable has been unset or is explicitly set to null. `empty()` checks for falsy values, while `defined()` is used for constants.