unset
(PHP 4, PHP 5)
unset — Unset a given variable
Description
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.
The above example will output:
If you would like to unset() a global variable
inside of a function, you can use
the $GLOBALS array to do so:
If a variable that is PASSED BY REFERENCE is
unset() inside of a function, only the local
variable is destroyed. The variable in the calling environment
will retain the same value as before unset()
was called.
The above example will output:
If a static variable is unset() inside of a
function, unset() destroys the variable only in the
context of the rest of a function. Following calls will restore the
previous value of a variable.
The above example will output:
Parameters
-
var
-
The variable to be unset.
-
var
-
Another variable ..
-
...
-
Return Values
No value is returned.
Examples
Example #1 unset() example
<?php
// destroy a single variable
unset($foo);
// destroy a single element of an array
unset($bar['quux']);
// destroy more than one variable
unset($foo1, $foo2, $foo3);
?>
Example #2 Using (unset) casting
<?php
$name = 'Felipe';
var_dump((unset) $name);
?>
Notes
Note: Because this is a
language construct and not a function, it cannot be called using
variable functions
Note:
It is possible to unset even object properties visible in current context.
Note:
It is not possible to unset $this inside an object
method since PHP 5.
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