php - 在 array_filter 中传递数组而不是回调

Question

我正在查看这个示例array_filter 注释，他将一个参数传递给 array_filter 作为

array_filter($subject, array(new array_ereg("image[0-9]{3}\.png"), 'ereg')

回调如何接受具有多个参数的数组，其中一个是实际的回调函数

Answer 1

In PHP it is possible to represent a callable using an array in the following format.

array($object, 'methodName')

The documentation itself states:

A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.

It is quite common to see this used with the $this variable inside objects.

In your example, the first element of the array is created with new, and is the instantiated object required, and ereg is the method.

Answer 2

The array_filter functions expects a callable for it's second parameter. PHP understands an array($instance, 'methodname') as callable for instance methods, and array('classname', 'staticmethodname') for static methods (or simple 'classname::staticmethod' since version 5.2.3 .

Answer 3

扩展其他答案。在 PHP >= 5.3 中，我们可以使用闭包。

$numbers = range(1,10);
$newNumbers = array_filter($numbers, function($value) {
    return ($value & 1) === false;
});
// $newNumbers now contains only even integers. 2, 4, 6, 8, 10.

Answer 4

查看PHP：回调页面。

当为可调用参数指定数组时，您正在指定一个对象和该对象的方法。例如：

$object = new MyClass();
array_filter($input, array($object, 'myClassMethod'));

在您提供的示例中：

array_filter($subject, array(new array_ereg("image[0-9]{3}\.png"), 'ereg');

array_ereg的新实例是对象，而ereg是 array_ereg 类的方法。