PHP“&"操作员 [英] PHP "&" operator

问题描述

我不是PHP程序员(但知道其他语言)，并且我试图了解一个用PHP(5.1.6)完成的网页，以便进行一些更改.

I'm not a PHP programmer (but know other languages), and I'm trying to understand a web page that was done in PHP (5.1.6) in order to do some changes.

页面具有以下代码(简体):

The page has the following code (simplified):

$db_hosts = array();
$sql = 'SELECT h.hostid, h.host FROM hosts h ';

$db_items = DBselect($sql);

while($db_item = DBfetch($db_items)){
    $name = $db_item['host'];
    $db_host = &$db_hosts[$db_item['hostid']];
}

我试图了解最后一行$db_host = &$db_hosts[$db_item['hostid']];.

似乎正在创建一个新变量$db_host，并在其中添加一些内容，但我不理解&$db_hosts.

It seems to be creating a new variable, $db_host, and putting something inside it, but I don't understand &$db_hosts.

我有疑问，因为据我所知，$db_hosts是一个空数组.

I'm in doubt because as far as I know, $db_hosts is an empty array.

我找到了 this 和

I found this and this, but I'm not quite sure, because in these links, the operator is "=&", and in the code, the operator is attached to the variable "= &$db_hosts" (it has an space between = and &).

由于我尝试修改它并没有成功，所以我认为最好寻求帮助...

Since I tried to modify it and didn't get success, I thought that it was better to ask for help...

推荐答案

这些都是引用，它们类似于C或C ++中的指针".

Those are references, and they are similar to "pointers" in C or C++.

更多信息，请参见 PHP手册.

在这种情况下，由于$db_hosts为空，因此构造$db_hosts[$db_item['hostid']]将创建一个新数组，该数组在$db_item['hostid']的索引上具有一个空项目，并返回该项目的引用，从而使$db_host充当别名" "表示当前的$db_hosts[$db_item['hostid']].

In this case, since $db_hosts is empty, the construct $db_hosts[$db_item['hostid']] will create a new array with an empty item on the index of $db_item['hostid'] and return the item's reference, making $db_host act as an 'alias' for whatever $db_hosts[$db_item['hostid']] is currently.

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