INIT_STRING
Please note, that you get no warnings on non-existent classes:
<?php
class A() {
}
$a = new A();
$exists = ($a instanceof A); //TRUE
$exists = ($a instanceof NonExistentClass); //FALSE
INSTANCEOF
PHP code
<?php
/*
*
* opcode number: 138
*/
$obj = new A();
if ($obj instanceof A) {
echo 'A';
}
?>
PHP opcodes
Function name: (null)
Compiled variables: !0=$obj
| line | # | op | fetch | ext | return | operands |
|---|---|---|---|---|---|---|
| 6 | 0 | ZEND_FETCH_CLASS | :0 | 'A' | ||
| 1 | NEW | $1 | :0 | |||
| 2 | DO_FCALL_BY_NAME | 0 | ||||
| 3 | ASSIGN | !0,$1 | ||||
| 8 | 4 | ZEND_FETCH_CLASS | :4 | 'A' | ||
| 5 | ZEND_INSTANCEOF | ~5 | !0,$4 | |||
| 6 | JMPZ | ~5,->9 | ||||
| 9 | 7 | ECHO | 'A' | |||
| 10 | 8 | JMP | ->9 | |||
| 11 | 9 | RETURN | 1 |
add a note
User Contributed Notes
INSTANCEOF - [2 notes]
asdf at asdf dot com ¶
1 year ago
cody at codysnider dot com ¶
10 months ago
When checking instanceof against a subclass of the class in question, it will return true.
<?php
class Foo {
public $foobar = 'Foo';
public function test() {
echo $this->foobar . "\n";
}
}
class Bar extends Foo {
public $foobar = 'Bar';
}
$a = new Foo();
$b = new Bar();
echo "use of test() method\n";
$a->test();
$b->test();
echo "instanceof Foo\n";
var_dump($a instanceof Foo); // TRUE
var_dump($b instanceof Foo); // TRUE
echo "instanceof Bar\n";
var_dump($a instanceof Bar); // FALSE
var_dump($b instanceof Bar); // TRUE
echo "subclass of Foo\n";
var_dump(is_subclass_of($a, 'Foo')); // FALSE
var_dump(is_subclass_of($b, 'Foo')); // TRUE
echo "subclass of Bar\n";
var_dump(is_subclass_of($a, 'Bar')); // FALSE
var_dump(is_subclass_of($b, 'Bar')); // FALSE
?>
Result (CLI, 5.4.4):
use of test() method
Foo
Bar
instanceof Foo
bool(true)
bool(true)
instanceof Bar
bool(false)
bool(true)
subclass of Foo
bool(false)
bool(true)
subclass of Bar
bool(false)
bool(false)