(PECL ds >= 1.0.0)
Ds\Deque::shift — Removes and returns the first value.
此函数没有参数。
The first value, which was removed.
UnderflowException if empty.
Example #1 Ds\Deque::shift() example
<?php
$deque = new \Ds\Deque(["a", "b", "c"]);
var_dump($deque->shift());
var_dump($deque->shift());
var_dump($deque->shift());
?>
以上例程的输出类似于：
string(1) "a" string(1) "b" string(1) "c"