如何检查变量是否是数组?...或类似数组的东西 [英] How to check if variable is array?... or something array-like
问题描述
我想对一个变量使用 foreach
循环,但是这个变量可以是许多不同的类型,例如 NULL
.
I want to use a foreach
loop with a variable, but this variable can be many different types, NULL
for example.
所以在 foreach
之前我测试了一下:
So before foreach
I test it:
if(is_array($var)){
foreach($var as ...
但我意识到它也可以是一个实现了Iterator
接口的类.也许我瞎了,但是如何检查类是否实现了接口?是否有类似 is_a
函数或 inherits
运算符的东西?我找到了 class_implements
,我可以使用它,但也许有更简单的东西?
But I realized that it can also be a class that implements Iterator
interface. Maybe I am blind but how to check whether the class implements interface? Is there something like is_a
function or inherits
operator? I found class_implements
, I can use it, but maybe there is something simpler?
第二,更重要的是,我认为这个函数存在,足以检查变量 is_array
或实现 Iterator
接口"还是我应该测试某些东西更多?
And second, more important, I suppose this function exist, would be enough to check if the variable is_array
or "implements Iterator
interface" or should I test for something more?
推荐答案
如果您在函数中使用 foreach
并且您需要一个数组或一个 Traversable 对象,你可以输入提示该函数:
If you are using foreach
inside a function and you are expecting an array or a Traversable object you can type hint that function with:
function myFunction(array $a)
function myFunction(Traversable)
如果您没有在函数内使用 foreach
或者您期望 你可以简单地使用这个结构来检查你是否可以迭代变量:
If you are not using foreach
inside a function or you are expecting both you can simply use this construct to check if you can iterate over the variable:
if (is_array($a) or ($a instanceof Traversable))
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