不能在php5.2中使用字符串偏移作为数组中断，而不是在php5.4中

Question

I've got this problem with php, and I guess the worst part is that it's working fine on my dev environment (php v5.4) but breaks on the test/live site on the webserver (php v5.2).

So when I var_dump my $_POST["formData"] I get an array that looks like this:

array(42) {
    [0] => array(2) {
        ["name"] => string(2) "id";
        ["value"] => string(4) "3972";
    }
    [1] => array(2) {
        ["name"] => string(2) "action";
        ["value"] => string(4) "edit";
    }
...
}

To separate this, I use this (or some variation of this):

for($i=0;$i<count($_POST["formData"]);$i++) {
    $data[$_POST["formData"][$i]["name"]] = $_POST["formData"][$i]["value"];
}

So I end up being able to access everything with:

foreach($data as $key => $value) {
    echo $key . " = " . $value . "<br />";
}

which outputs:

id = 3972
action = edit
...

So, again, this works just fine on my dev server, but breaks on the live site. I've looked around here and found a lot of examples, but it seems a lot of them are using examples that aren't working quite the same.

What's causing this? Is it some setting? Is it a change between the two versions? I've tried a couple other things but none of them have worked and it's kinda a pain testing on the testing server (uploading files one at a time...yay...). Any easy solution or do I have to rebuild my script?

Answer 1

That error suggests you're using a string as if it were an array. I'll assume it's your for loop. I'm not entirely sure, but $data could be being implicitly initialised to an empty string, which you are then trying to dereference and assign to. Does rewriting it like this help?

$data = array();    
foreach($_POST['formData'] as $kvp) {
    $data[$kvp['name']] = $kvp['value'];
}

This code is also faster, because you're not calling count() in a loop.

Answer 2

It turns out this is indeed a difference between PHP versions, as demonstrated by this handy comparison tool .

For reference, the somewhat confusing error comes about (prior to PHP 5.4) from the following two steps:

1. You take a variable that you think is an array, but is actually a string, and you access an "element" of it, eg $foo[1] or $foo['bar'] . PHP takes this to mean "get the Nth character of the string" - $foo[1] means the 2nd character of $foo , and $foo['bar'] means the first, because the bar gets converted to 0 .
2. You then access that as though it's an array. Newer versions of PHP just repeat step 1 on the 1-character string you ended up with, but until PHP 5.4 this caused the ugly error.

So in some situations, your $_POST["formData"] is not an array, but a string. This is probably happening sometimes on both environments, but the difference in error handling is masking it in one environment and not the other.