json_encode返回不确定的结果，数组或对象[重复]

Question

This question already has an answer here:

• PHP json_encode - Strange behaviour 4 answers

I find a weird result of json_encode today in my production code, sometimes it returns an array, like ["perl","php","python"], but sometimes an object, like {"0":"perl","2":"python"}. Here is a minimal example:

$a = array("perl", "php", "python", "something other");
foreach($a as $index => $item) 
{
    if ($item == "something")
        unset($a[$index]);
}
echo json_encode($a);

Why does this happen?

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Answer 1

In the foreach loop, once $item == "something" is true, the array keys are not consecutively numerically indexed (except last iteration), then json_encode returns an object. If all the values in the array are not equal to "something", it returns an array. Since array is always what I want, I use array_values() before json_encode.