Ds\Sequence::filter

(PECL ds >= 1.0.0)

Ds\Sequence::filter — Creates a new sequence using a callable to determine which values to include

说明

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

Creates a new sequence 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 sequence 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

Example #1 Ds\Sequence::filter() example using callback function


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

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

以上例程的输出类似于：

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

Example #2 Ds\Sequence::filter() example without a callback function


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

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

以上例程的输出类似于：

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

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