reset()

(PHP 4, PHP 5, PHP 7)

将数组的内部指针指向第一个单元

说明

reset()将$array的内部指针倒回到第一个单元并返回第一个数组单元的值。

参数

输入的数组。

返回值

返回数组第一个单元的值，如果数组为空则返回FALSE。

范例

Example #1reset()例子

参见

• current() 返回数组中的当前单元
• each() 返回数组中当前的键／值对并将数组指针向前移动一步
• end() 将数组的内部指针指向最后一个单元
• next() 将数组中的内部指针向前移动一位
• prev() 将数组的内部指针倒回一位

GOTCHA: If your first element is false, you don't know whether it was empty or not.

So don't count on a false return being an empty array.

As for taking first key of an array, it's much more efficient to RESET and then KEY, rather then RESET result of ARRAY_KEYS (as sugested by gardnerjohng at gmail dot com).

This will give the same result but is much much faster. Larger arrays, better performance. Tested on 100-elements long array with 16 times faster results.

When used on a scalar or unset value, reset() spews warning messages. This is often a problem when accessing arrays generated from HTML form input data: these are scalar or unset if the user didn't enter sufficient information.
You can silence these error messages by prefixing an @ (at sign) to reset(), but it is better style to protect your reset() and the following array traversal with an if (isset()). Example code:

鹏仔微信 15129739599 鹏仔QQ344225443 鹏仔前端 pjxi.com 共享博客 sharedbk.com