ͨ�������б���Դ�����Ϣ�����������Զ�����Ϊ�ָ����ı��ʽ�б������Ǵ���������ֵ�ġ�
PHP ֧�ְ�ֵ���ݲ�����Ĭ�ϣ���ͨ�����ô��ݲ����Լ�Ĭ�ϲ�����Ҳ֧���ɱ䳤�Ȳ����б���
Example #1 ������������
<?php
function takes_array($input)
{
echo "$input[0] + $input[1] = ", $input[0]+$input[1];
}
?>
Ĭ������£���������ͨ��ֵ���ݣ������ʹ�ں����ڲ��ı������ֵ����������ı亯���ⲿ��ֵ�������ϣ�������������IJ���ֵ������ͨ�����ô��ݲ�����
�����Ҫ������һ����������ͨ�����ô��ݣ������ں��������иò�����ǰ����Ϸ��� &��
Example #2 �����ô��ݺ�������
<?php
function add_some_extra(&$string)
{
$string .= 'and something extra.';
}
$str = 'This is a string, ';
add_some_extra($str);
echo $str; // outputs 'This is a string, and something extra.'
?>
�������Զ��� C++ ���ı�������Ĭ��ֵ��������ʾ��
Example #3 �ں�����ʹ��Ĭ�ϲ���
<?php
function makecoffee($type = "cappuccino")
{
return "Making a cup of $type.\n";
}
echo makecoffee();
echo makecoffee(null);
echo makecoffee("espresso");
?>
�������̻������
Making a cup of cappuccino. Making a cup of . Making a cup of espresso.
PHP ������ʹ������ array ���������� NULL
��ΪĬ�ϲ��������磺
Example #4 ʹ�÷DZ���������ΪĬ�ϲ���
<?php
function makecoffee($types = array("cappuccino"), $coffeeMaker = NULL)
{
$device = is_null($coffeeMaker) ? "hands" : $coffeeMaker;
return "Making a cup of ".join(", ", $types)." with $device.\n";
}
echo makecoffee();
echo makecoffee(array("cappuccino", "lavazza"), "teapot");
?>
Ĭ��ֵ�����dz������ʽ��������������������Ա�����ߺ������õȡ�
ע�ʹ��Ĭ�ϲ���ʱ���κ�Ĭ�ϲ�����������κη�Ĭ�ϲ������Ҳࣻ�����������ᰴ��Ԥ�ڵ������������������Ĵ���Ƭ�ϣ�
Example #5 ����Ĭ�ϲ����IJ���ȷ�÷�
<?php
function makeyogurt($type = "acidophilus", $flavour)
{
return "Making a bowl of $type $flavour.\n";
}
echo makeyogurt("raspberry"); // won't work as expected
?>
�������̻������
Warning: Missing argument 2 in call to makeyogurt() in /usr/local/etc/httpd/htdocs/phptest/functest.html on line 41 Making a bowl of raspberry .
���ڣ��Ƚ���������Ӻ�������ӣ�
Example #6 ����Ĭ�ϲ�����ȷ���÷�
<?php
function makeyogurt($flavour, $type = "acidophilus")
{
return "Making a bowl of $type $flavour.\n";
}
echo makeyogurt("raspberry"); // works as expected
?>
�������̻������
Making a bowl of acidophilus raspberry.
Note: �� PHP 5 �𣬴����õIJ���Ҳ������Ĭ��ֵ��
Note:
��PHP 5�У���������Ҳ����Ϊ������ʾ��
���������������ڵ���ʱҪ�����Ϊ�ض����͡� ���������ֵ���Ͳ��ԣ���ô�������һ������ ��PHP 5�У��⽫��һ���ɻָ�������������PHP 7�н����׳�һ��TypeError�쳣��
Ϊ��ָ��һ����������������Ӧ�üӵ�������ǰ�������������ͨ����������Ĭ��ֵ��ΪNULL
��ʵ��������NULL
��
Type | Description | Minimum PHP version |
---|---|---|
Class/interface name | The parameter must be an instanceof the given class or interface name. | PHP 5.0.0 |
self | The parameter must be an instanceof the same class as the one the method is defined on. This can only be used on class and instance methods. | PHP 5.0.0 |
array | The parameter must be an array. | PHP 5.1.0 |
callable | The parameter must be a valid callable. | PHP 5.4.0 |
bool | The parameter must be a boolean value. | PHP 7.0.0 |
float | The parameter must be a floating point number. | PHP 7.0.0 |
int | The parameter must be an integer. | PHP 7.0.0 |
string | The parameter must be a string. | PHP 7.0.0 |
Aliases for the above scalar types are not supported. Instead, they are treated as class or interface names. For example, using boolean as a parameter or return type will require an argument or return value that is an instanceof the class or interface boolean, rather than of type bool:
<?php
function test(boolean $param) {}
test(true);
?>
�������̻������
Fatal error: Uncaught TypeError: Argument 1 passed to test() must be an instance of boolean, boolean given, called in - on line 1 and defined in -:1
Example #7 Basic class type declaration
<?php
class C {}
class D extends C {}
// This doesn't extend C.
class E {}
function f(C $c) {
echo get_class($c)."\n";
}
f(new C);
f(new D);
f(new E);
?>
�������̻������
C D Fatal error: Uncaught TypeError: Argument 1 passed to f() must be an instance of C, instance of E given, called in - on line 14 and defined in -:8 Stack trace: #0 -(14): f(Object(E)) #1 {main} thrown in - on line 8
Example #8 Basic interface type declaration
<?php
interface I { public function f(); }
class C implements I { public function f() {} }
// This doesn't implement I.
class E {}
function f(I $i) {
echo get_class($i)."\n";
}
f(new C);
f(new E);
?>
�������̻������
C Fatal error: Uncaught TypeError: Argument 1 passed to f() must implement interface I, instance of E given, called in - on line 13 and defined in -:8 Stack trace: #0 -(13): f(Object(E)) #1 {main} thrown in - on line 8
Example #9 Nullable type declaration
<?php
class C {}
function f(C $c = null) {
var_dump($c);
}
f(new C);
f(null);
?>
�������̻������
object(C)#1 (0) { } NULL
Ĭ������£�����������Ļ���PHP����ǿ�ȴ������͵�ֵתΪ���������ı������͡� ���磬һ��������һ������������string�����������integer�����պ����õ��Ľ�����һ��string���͵�ֵ��
���Ի���ÿһ���ļ������ϸ�ģʽ�����ϸ�ģʽ�У�ֻ��һ��������������ȫ����ı����Żᱻ���ܣ������׳�һ��TypeError�� Ψһ��һ�������ǿ��Խ�integer����һ������float�ĺ�����
ʹ�� declare ����strict_types �����������ϸ�ģʽ��
�����ϸ�ģʽͬʱҲ��Ӱ������ֵ��������.
Note:
�ϸ������������������ϸ�ģʽ���ļ����ĺ������ã����������Ǹ��ļ��������ĺ����� һ��û�������ϸ�ģʽ���ļ��ڵ�����һ���������ϸ�ģʽ���ļ��ж���ĺ�������ô������ѭ�����ߵ�ƫ�ã������ͣ��������ֵ���ᱻת����
Note:
�ϸ����ͽ����ڱ�������������Ҳ������Ϊ��ˣ�����ҪPHP 7.0.0 ����°汾����Ϊ������������Ҳ�����Ǹ��汾����ӵġ�
Example #10 Strict typing
<?php
declare(strict_types=1);
function sum(int $a, int $b) {
return $a + $b;
}
var_dump(sum(1, 2));
var_dump(sum(1.5, 2.5));
?>
�������̻������
int(3) Fatal error: Uncaught TypeError: Argument 1 passed to sum() must be of the type integer, float given, called in - on line 9 and defined in -:4 Stack trace: #0 -(9): sum(1.5, 2.5) #1 {main} thrown in - on line 4
Example #11 Weak typing
<?php
function sum(int $a, int $b) {
return $a + $b;
}
var_dump(sum(1, 2));
// These will be coerced to integers: note the output below!
var_dump(sum(1.5, 2.5));
?>
�������̻������
int(3) int(3)
Example #12 Catching TypeError
<?php
declare(strict_types=1);
function sum(int $a, int $b) {
return $a + $b;
}
try {
var_dump(sum(1, 2));
var_dump(sum(1.5, 2.5));
} catch (TypeError $e) {
echo 'Error: '.$e->getMessage();
}
?>
�������̻������
int(3) Error: Argument 1 passed to sum() must be of the type integer, float given, called in - on line 10
PHP ���û��Զ��庯����֧�ֿɱ������IJ����б��� PHP 5.6 �����ϵİ汾�У��� ... �ʵ�֣��� PHP 5.5 ������汾�У�ʹ�ú��� func_num_args()��func_get_arg()���� func_get_args() ��
In PHP 5.6 and later, argument lists may include the ... token to denote that the function accepts a variable number of arguments. The arguments will be passed into the given variable as an array; for example:
Example #13 Using ... to access variable arguments
<?php
function sum(...$numbers) {
$acc = 0;
foreach ($numbers as $n) {
$acc += $n;
}
return $acc;
}
echo sum(1, 2, 3, 4);
?>
�������̻������
10
You can also use ... when calling functions to unpack an array or Traversable variable or literal into the argument list:
Example #14 Using ... to provide arguments
<?php
function add($a, $b) {
return $a + $b;
}
echo add(...[1, 2])."\n";
$a = [1, 2];
echo add(...$a);
?>
�������̻������
3 3
You may specify normal positional arguments before the ... token. In this case, only the trailing arguments that don't match a positional argument will be added to the array generated by ....
It is also possible to add a type hint before the ... token. If this is present, then all arguments captured by ... must be objects of the hinted class.
Example #15 Type hinted variable arguments
<?php
function total_intervals($unit, DateInterval ...$intervals) {
$time = 0;
foreach ($intervals as $interval) {
$time += $interval->$unit;
}
return $time;
}
$a = new DateInterval('P1D');
$b = new DateInterval('P2D');
echo total_intervals('d', $a, $b).' days';
// This will fail, since null isn't a DateInterval object.
echo total_intervals('d', null);
?>
�������̻������
3 days Catchable fatal error: Argument 2 passed to total_intervals() must be an instance of DateInterval, null given, called in - on line 14 and defined in - on line 2
Finally, you may also pass variable arguments by reference by prefixing the ... with an ampersand (&).
No special syntax is required to note that a function is variadic; however access to the function's arguments must use func_num_args(), func_get_arg() and func_get_args().
The first example above would be implemented as follows in PHP 5.5 and earlier:
Example #16 Accessing variable arguments in PHP 5.5 and earlier
<?php
function sum() {
$acc = 0;
foreach (func_get_args() as $n) {
$acc += $n;
}
return $acc;
}
echo sum(1, 2, 3, 4);
?>
�������̻������
10