Ds\Map::first

(PECL ds >= 1.0.0)

Ds\Map::first — Returns the first pair in the map

说明

public Ds\Map::first ( void ) : Ds\Pair

Returns the first pair in the map.

参数

此函数没有参数。

返回值

The first pair in the map.

错误／异常

UnderflowException if empty.

范例

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

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

以上例程的输出类似于：

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