Creates a new set using a callable to determine which values to include

说明

public Ds\Set::filter ( callable $callback = ? ) : Ds\Set

Creates a new set using a callable to determine which values to include.

参数

callback

callback ( mixed $value ) : bool

Optional callable which returns true if the value should be included, false otherwise.

If a callback is not provided, only values which are true (see converting to boolean) will be included.

返回值

A new set containing all the values for which either the callback returned true, or all values that convert to true if a callback was not provided.

范例

示例 #1 Ds\Set::filter() example using callback function


<?php
$set = new \Ds\Set([1, 2, 3, 4, 5]);

var_dump($set->filter(function($value) {
    return $value % 2 == 0;
}));
?>

以上例程的输出类似于：

object(Ds\Set)#3 (2) {
  [0]=>
  int(2)
  [1]=>
  int(4)
}

示例 #2 Ds\Set::filter() example without a callback function


<?php
$set = new \Ds\Set([0, 1, 'a', true, false]);

var_dump($set->filter());
?>

以上例程的输出类似于：

object(Ds\Set)#2 (3) {
  [0]=>
  int(1)
  [1]=>
  string(1) "a"
  [2]=>
  bool(true)
}