unset code on php

Description

int unset (mixed var [, mixed var [, ...]])

unset() destroys the specified variables and returns true.

Example 1. Unset() example
// destroy a single variable unset ($foo); // destroy a single element of an array unset ($bar['quux']); // destroy more than one variable unset ($foo1, $foo2, $foo3);

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.

function destroy_foo() {     global $foo;     unset($foo); }  $foo = 'bar'; destroy_foo(); echo $foo;

The above example would output:

bar

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.

function foo(&$bar) {      unset($bar);      $bar = "blah";  }  $bar = 'something'; echo "$bar\n";  foo($bar); echo "$bar\n";

The above example would output:

something something

If a static variable is unset() inside of a function, unset() unsets the reference to the static variable, rather than the static variable itself.

function foo() {      static $a;     $a++;        echo "$a\n";      unset($a); }  foo(); foo(); foo();

The above example would output:

1 2 3

If you would like to unset() a global variable inside of a function, you can use the $GLOBALS array to do so:

function foo() {     unset($GLOBALS['bar']);        }  $bar = "something"; foo();