# Ds\Map::keys

(PECL ds >= 1.0.0)

Ds\Map::keys — Returns a set of the map's keys

### 说明

public Ds\Map::keys(): Ds\Set

Returns a set containing all the keys of the map, in the same order.

### 参数

此函数没有参数。

### 返回值

A Ds\Set containing all the keys of the map.

### 示例

示例 #1 Ds\Map::keys() example

`<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
var_dump($map->keys());
?>`

以上示例的输出类似于：

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

`↑` and `↓` to navigate • `Enter` to select • `Esc` to close • `/` to open