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Ds\Map::intersect

(PECL ds >= 1.0.0)

Ds\Map::intersect — Creates a new map by intersecting keys with another map

说明

public Ds\Map::intersect ( Ds\Map $map ) : Ds\Map

Creates a new map containing the pairs of the current instance whose keys are also present in the given map. In other words, returns a copy of the current instance with all keys removed that are not also in the other map.

A ∩ B = {x : x ∈ A ∧ x ∈ B}

Note:

Values from the current instance will be kept.

参数

map

The other map, containing the keys to intersect with.

返回值

The key intersection of the current instance and another map.

See Also

范例

Example #1 Ds\Map::intersect() example

<?php
$a = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
$b = new \Ds\Map(["b" => 4, "c" => 5, "d" => 6]);

var_dump($a->intersect($b));
?>

以上例程的输出类似于：

object(Ds\Map)#3 (2) {
  [0]=>
  object(Ds\Pair)#4 (2) {
    ["key"]=>
    string(1) "b"
    ["value"]=>
    int(2)
  }
  [1]=>
  object(Ds\Pair)#5 (2) {
    ["key"]=>
    string(1) "c"
    ["value"]=>
    int(3)
  }
}