Ds\Queue::peek

(PECL ds >= 1.0.0)

Ds\Queue::peekReturns the value at the front of the queue

说明

public mixed Ds\Queue::peek ( void )

Returns the value at the front of the queue, but does not remove it.

参数

此函数没有参数。

返回值

The value at the front of the queue.

错误/异常

UnderflowException if empty.

范例

Example #1 Ds\Queue::peek() example

<?php
$queue 
= new \Ds\Queue();

$queue->push("a");
$queue->push("b");
$queue->push("c");

var_dump($queue->peek());
?>

以上例程的输出类似于:

string(1) "a"
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