(PECL ds >= 1.0.0)
Ds\Map::hasKey — Determines whether the map contains a given key
keyThe key to look for.
Returns true if the key could found, false otherwise.
Example #1 Ds\Map::hasKey() example
<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
var_dump($map->hasKey("a")); // true
var_dump($map->hasKey("e")); // false
?>
以上例程的输出类似于：
bool(true) bool(false)