unset()

unset() "undeclares" a previously set variable, and frees any memory that was used by it if no other variable references its value. A call to isset() on a variable that has been unset() returns false.

For example:

$name = "John Doe";<span class="fullpost">
unset($name);
if (isset($name)) {
    print '$name is set';
}

This example will not generate any output, because isset() returns false.

unset() can also be used on array elements and object properties similar to isset().</span>