php 中哪个更快且占用资源更少？
For every 和 while，推荐哪个更快，它们的资源使用情况如何？
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for vs foreach vs while which is faster for iterating through arrays in php
For each and while, which of these is faster, recommended, and what are their resource usages like?
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foreach针对集合迭代进行了优化。这是一种奇特的说法，当您将它与数组（以及从 PHP5 开始，对象）一起使用时，它效果最好（也是最快）。您可以使用while()获得与 foreach 相同的效果，但效率不高，因为您需要在while内调用list()代码>循环。用
while编写的foreach($array as $key => $value)是while(list($key,$value) = every($array ））。您可以看到需要的额外呼叫数量。foreachis optimized for iteration over collections. That's a fancy way of saying that it works best (and fastest) when you use it with arrays (and as of PHP5, objects). You can usewhile()to get the same effect as a foreach, but its not as efficient since you need to calllist()inside thewhileloop.foreach($array as $key => $value)written with awhileiswhile(list($key,$value) = each($array)). You can see the number of extra calls that are needed.我认为他们应该有相同的速度。
我更喜欢 foreach 因为它更安全。
i think they should have the same speed.
i prefer foreach because its safer.
这可能取决于您如何使用它们。您可以选择通过引用
foreach循环来传递数组。在这种情况下，将不会复制整个数组。像这样的优化可能比在foreach和while之间进行选择更有效。That may depend on how you use them exactly. You can choose to pass an array by reference to the
foreachloop. In that case there will not be made a copy of the entire array. Optimizations like this probably have more effect than choosing betweenforeachandwhile.