PHP, null (NULL)

1. Null value (NULL)

A null value, the name Incredibles, indicates that no value is set for the variable. In addition, null values (NULL) are not case-sensitive, and null and null effects are the same. The null value is given in the following 3: No value has been assigned, NULL has been assigned, and the variable that has been processed by the UNSET function has been evaluated.

The 2.is_null function is used to determine whether a variable is NULL, the function returns a Boolean, or True if the variable is null, otherwise the False.unset function is used to destroy the specified variable.

PHP, null (NULL)