Creates a new map using keys that aren't in another map

# Ds\Map::diff

(PECL ds >= 1.0.0)

Ds\Map::diff — Creates a new map using keys that aren't in another map

### 説明

public Ds\Map::diff ( Ds\Map `$map` ) : Ds\Map

Returns the result of removing all keys from the current instance that are present in a given `map`.

`A \ B = {x ∈ A | x ∉ B}`

### パラメータ

`map`

  The map containing the keys to exclude in the resulting map.

### 返り値

The result of removing all keys from the current instance that are present in a given `map`.

### See Also

- » Compliment on Wikipedia

### 例

例1 Ds\Map::diff() 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->diff($b));
?>`

上の例の出力は、 たとえば以下のようになります。

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