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unset

unset

unset a given variable

void **unset** mixed $var mixed $vars

destroys the specified variables.

unset

The behavior of inside of a function can vary depending on what type of variable you are attempting to destroy. unset

If a globalized variable is inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before was called.

unset``unset**Voorbeeld: Using **

<?php
function destroy_foo() 
{
    global $foo;
    unset($foo);
}

$foo = 'bar';
destroy_foo();
echo $foo;
?>

To a global variable inside of a function, then use the array to do so:

unset``$GLOBALSVoorbeeld: a Global Variable

<?php
function foo() 
{
    unset($GLOBALS['bar']);
}

$bar = "something";
foo();
?>

If a variable that is PASSED BY REFERENCE is inside of a function, only the local variable is destroyed. The variable in the calling environment will retain the same value as before was called.

unset``unsetVoorbeeld: with Reference

<?php
function foo(&$bar) 
{
    unset($bar);
    $bar = "blah";
}

$bar = 'something';
echo "$bar\n";

foo($bar);
echo "$bar\n";
?>

If a static variable is inside of a function, destroys the variable only in the context of the rest of a function. Following calls will restore the previous value of a variable.

unset``unsetVoorbeeld: with Static Variable

<?php
function foo()
{
    static $bar;
    $bar++;
    echo "Before unset: $bar, ";
    unset($bar);
    $bar = 23;
    echo "after unset: $bar\n";
}

foo();
foo();
foo();
?>

varThe variable to be unset.

varsFurther variables.

return.void

Voorbeeld: 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);
?>

Opmerking: > It is possible to unset object properties visible in the current context.

 If declared,
 
 is called when accessing an unset property, and
 
 is called when setting an unset property.

__get()__set()

Opmerking: > It is not possible to unset inside an object method. $this

Opmerking: > When using on inaccessible object properties, the overloading method will be called, if declared. unset__unset()

isset``empty__unset()array_splice(unset) casting

Vorige ← unserialize Volgende var_dump →

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