unset

Example

 void unset ( mixed $var [, mixed $... ] ) 

Description

unset() destroys the specified variables. The behavior of unset() inside of a function can vary depending on what type of variable you are attempting to destroy. If a globalized variable is unset() inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before unset() was called.
<?phpfunction destroy_foo() {    global $foo;    unset($foo);}$foo = 'bar';destroy_foo();echo $foo;?>

The above example will output:
bar
To unset() a global variable inside of a function, then use the $GLOBALS array to do so:
<?phpfunction foo() {    unset($GLOBALS['bar']);}$bar = "something";foo();?>

If a variable that is PASSED BY REFERENCE is unset() inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before unset() was called.
<?phpfunction foo(&$bar) {    unset($bar);    $bar = "blah";}$bar = 'something';echo "$bar\n";foo($bar);echo "$bar\n";?>

The above example will output:
something something
If a static variable is unset() inside of a function, unset() destroys the variable only in the context of the rest of a function. Following calls will restore the previous value of a variable.
<?phpfunction foo(){    static $bar;    $bar++;    echo "Before unset: $bar, ";    unset($bar);    $bar = 23;    echo "after unset: $bar\n";}foo();foo();foo();?>

The above example will output:
Before unset: 1, after unset: 23 Before unset: 2, after unset: 23 Before unset: 3, after unset: 23

Return Values

No value is returned.