PHP关联数组

I'm having some problems assigning values to a PHP array. I've read the help files and numerous articles here and I'm even more confused.

I have an HTML order form that's processed by PHP. The user enters the quantity, and, if necessary, a free text description of the item. Not all items have a free text description. The POST output is:

[_POST] => Array
    (
        [items_1] => 
        [items_2] => 
        [items_21] => 
        [items_68] => 
        [items_94] => 
        [items_501] => 2
        [txt_501] => Laserjet
        [items_510] => 
        [txt_510] => Item Description
        [items_511] => 
        [txt_511] => Item Description
        [PlaceOrder] => Place Your Order
    )

The value side of the items element is non-zero if the user entered a quantity on the form. The value side of the txt element can be user-entered or the default field description.

The object is to end up with an array of items which I can add to an orders database, ideally in the format "array(itemno)=count,txt" where itemno is the part to the right of the underscore, count is > 0 and txt is the value part of the txt element if there is a corresponding count. For this sample, the desired output would be items("501")="2,Laserjet"

My PHP code is:

foreach($_POST as $key => $value) {
    $_POST[$key] = filter($value); //POST variables are filtered for bad input
    $x = explode("_", $key);
    $itemno=$x[1];
    if ($x[0] = "txt") { $desc = $value; }
    if ($x[0] = "items") { $count = $value; }
    echo $itemno,"|", $count,"|",$desc,"|<br/>";
    if (($count > 0) and ($itemno > 0)) { $items[$itemno] = $count;}
}

I have reduced this down to that last line of code, and it doesn't work.

What the heck am I doing wrong?

Changing these two lines:

if ($x[0] = "txt") { $desc = $value; }
if ($x[0] = "items") { $count = $value; }

to something like:

if ($x[0] == "txt") { $items[$itemno][1] = $value; }
elseif ($x[0] == "items") { $items[$itemno][0] = $value; }

and completely dropping that last line should make you get the items array like this:

$items[501] = array(2, 'Lasetjet');

Which is then easy to convert into 2, Laserjet.

So, the full code would look like this:

foreach($_POST as $key => $value) {
    $_POST[$key] = filter($value); //POST variables are filtered for bad input
    $x = explode("_", $key);
    $itemno = $x[1];
    if ($x[0] == "txt") { $items[$itemno][1] = $value; }
    elseif ($x[0] == "items") { $items[$itemno][0] = $value; }
}

var_dump($items); // see the whole array

UPDATE

Noticed a huge error - you were using the assignment operator (=) instead of comparison (==).

See the full working example here: http://ideone.com/kETOvZ

It would be better to change your HTML so that the input names are in array syntax:

Item # 1: Count: <input type="text" name="item[1]"/> Description: <input type="text" name="txt[1]"/><br/>
Item # 21: Count: <input type="text" name="item[21]"/> Description: <input type="text" name="txt[21]"/><br/>
...

PHP will then create put these into sub-arrays in $_POST, and you can do this:

$items = array();
foreach ($_POST['item'] AS $itemno => $count) {
    echo $itemno, "|", $count, "|", $_POST['txt'][$itemno], "|<br/>";
    $items[$itemno] = array('count' => $count, 'txt' => $_POST['txt'][$itemno]);
}