带参数的PHP array_filter

我有以下代码：

function lower_than_10($i) { return ($i < 10); } 

我可以用来像这样过滤一个数组：

 $arr = array(7, 8, 9, 10, 11, 12, 13); $new_arr = array_filter($arr, 'lower_than_10'); 

我怎样才能将参数添加到lower_than_10，以便它也接受检查的号码？ 就像，如果我有这个：

 function lower_than($i, $num) { return ($i < $num); } 

如何从array_filter调用它传递10到$ num或任何数字？

Answer 1

作为使用闭包的 @ Charles 解决scheme的替代scheme ，您实际上可以在文档页面的注释中find一个示例。 这个想法是你创build一个具有所需状态（ $num ）和callback方法（以$i为参数）的对象：

 class LowerThanFilter { private $num; function __construct($num) { $this->num = $num; } function isLower($i) { return $i < $this->num; } } 

用法（ 演示 ）：

 $arr = array(7, 8, 9, 10, 11, 12, 13); $matches = array_filter($arr, array(new LowerThanFilter(12), 'isLower')); print_r($matches); 

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作为一个旁注，你现在可以用一个更通用的NumericComparisonFilterreplaceLowerThanFilter ，像isLower ， isGreater ， isEqual等方法。只是一个想法和演示 …

Answer 2

如果你使用php 5.3及以上版本，你可以使用closure来简化你的代码：

 $NUM = 5; $items = array(1, 4, 5, 8, 0, 6); $filteredItems = array_filter($items, function($elem) use($NUM){ return $elem < $NUM; }); 

Answer 3

在PHP 5.3或更高版本中，您可以使用闭包 ：

 function create_lower_than($number = 10) { // The "use" here binds $number to the function at declare time. // This means that whenever $number appears inside the anonymous // function, it will have the value it had when the anonymous // function was declared. return function($test) use($number) { return $test < $number; }; } // We created this with a ten by default. Let's test. $lt_10 = create_lower_than(); var_dump($lt_10(9)); // True var_dump($lt_10(10)); // False var_dump($lt_10(11)); // False // Let's try a specific value. $lt_15 = create_lower_than(15); var_dump($lt_15(13)); // True var_dump($lt_15(14)); // True var_dump($lt_15(15)); // False var_dump($lt_15(16)); // False // The creation of the less-than-15 hasn't disrupted our less-than-10: var_dump($lt_10(9)); // Still true var_dump($lt_10(10)); // Still false var_dump($lt_10(11)); // Still false // We can simply pass the anonymous function anywhere that a // 'callback' PHP type is expected, such as in array_filter: $arr = array(7, 8, 9, 10, 11, 12, 13); $new_arr = array_filter($arr, $lt_10); print_r($new_arr); 

Answer 4

在扩展到jensgram的答案中，你可以使用__invoke()魔术方法添加更多的魔法。

 class LowerThanFilter { private $num; public function __construct($num) { $this->num = $num; } public function isLower($i) { return $i < $this->num; } function __invoke($i) { return $this->isLower($i); } } 

这将允许你做

 $arr = array(7, 8, 9, 10, 11, 12, 13); $matches = array_filter($arr, new LowerThanFilter(12)); print_r($matches); 

Answer 5

如果需要传递给函数的多个参数，可以使用“，”将它们附加到use语句中：

 $r = array_filter($anArray, function($anElement) use ($a, $b, $c){ //function body where you may use $anElement, $a, $b and $c }); 

Answer 6

 class ArraySearcher{ const OPERATOR_EQUALS = '=='; const OPERATOR_GREATERTHAN = '>'; const OPERATOR_LOWERTHAN = '<'; const OPERATOR_NOT = '!='; private $_field; private $_operation; private $_val; public function __construct($field,$operation,$num) { $this->_field = $field; $this->_operation = $operation; $this->_val = $num; } function __invoke($i) { switch($this->_operation){ case '==': return $i[$this->_field] == $this->_val; break; case '>': return $i[$this->_field] > $this->_val; break; case '<': return $i[$this->_field] < $this->_val; break; case '!=': return $i[$this->_field] != $this->_val; break; } } } 

这使您可以筛选multidimensional array中的项目：

 $users = array(); $users[] = array('email' => '[e-mail]','name' => 'Robert'); $users[] = array('email' => '[e-mail]','name' => 'Carl'); $users[] = array('email' => '[e-mail]','name' => 'Robert'); //Print all users called 'Robert' print_r( array_filter($users, new ArraySearcher('name',ArraySearcher::OPERATOR_EQUALS,'Robert')) );