PHP - 空数组
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PHP - empty array
提问by Alex
(array)$someemptyvariablethatisnotarrayreturns array([0] =>)instead of array()
(array)$someemptyvariablethatisnotarray返回array([0] =>)而不是array()
How can I make it so I get a empty array that is not iterated when I'm using it inside foreach() ?
我怎样才能得到一个空数组，当我在 foreach() 中使用它时，它不会被迭代？
回答by trickwallett
$var = array();
will empty an array. Is this what you're after?
将清空一个数组。这是你追求的吗？
回答by powtac
The feature which you are using, is called "casting". This means a variable is forced to become a given type, in your example an array. How the var is converted is not always obvious in PHP!
您正在使用的功能称为“铸造”。这意味着变量被迫成为给定类型，在您的示例中为数组。在 PHP 中如何转换 var 并不总是很明显！
In your example $someemptyvariablethatisnotarray becomes an array with one entry with a NULL value.
在您的示例中， $someemptyvariablethatisnotarray 成为一个数组，其中一个条目为 NULL 值。
The PHP documentationsays:
在PHP文件说：
The behaviour of an automatic conversion to array is currently undefined.
自动转换为数组的行为目前未定义。
To solve your code I would recommend something like this:
为了解决您的代码，我建议您这样做：
if (!is_array($someemptyvariablethatisnotarray) {
$someemptyvariablethatisnotarray = array();
}
回答by sharpner
if(!$variable){
return array();
}
回答by Brad Christie
$somevar = empty($somevar) ? array() : (array)$somevar;
Maybe? Though I'm not sure I get the cast, or the purpose. Care to ellaborate a bit more (maybe an example of what you're trying to accomplish?)
也许？虽然我不确定我是否得到了演员或目的。小心详细说明一点（也许是你想要完成的一个例子？）
回答by beta0x64
Try unset($someemptyvariablethatisnotarray[0]):)
试试unset($someemptyvariablethatisnotarray[0]):)
回答by fsodano
how are you?
你好吗？
I believe this is what you're after:
我相信这就是你所追求的：
$something = false;
foreach((array)(empty($something) ? null : $something) as $k){
echo 'never enters here';
}
You don't get an empty array, because when you set "(array)false", it means you'll have a single element, and that element will have the "FALSE" value assigned to it.
您不会得到一个空数组，因为当您设置“(array)false”时，这意味着您将拥有一个元素，并且该元素将分配给它的“FALSE”值。
Same happens with an empty string (not a null one!)(array)$emptystring will return an array which contains a single element, which is an empty string!
空字符串也会发生同样的情况（不是空字符串！）(array)$emptystring 将返回一个包含单个元素的数组，这是一个空字符串！
Similar to doing:
类似于做：
array('');
Hope it helps.
希望能帮助到你。
Cheers!
干杯!
回答by Rocket Hazmat
When you cast a non-array as an array, it creates an array with that variable as the only value.
当您将非数组转换为数组时，它会创建一个以该变量作为唯一值的数组。
If you want an empty array, you need to return array().
如果你想要一个空数组，你需要返回array().
回答by james
just use count(), for example: if(count($array) == 0 ){ // empty array }
只需使用count()，例如：if(count($array) == 0 ){ // empty array }
