PHP嵌套数组循环与数组更新

I'm from a VB; Access; SQL Server background recently introduced to WAMP. I have a problem which I have not been able to solve for a few weeks now, I think I have visited every forum on the web (including here) without success.

I have two arrays filled from MySQL recordsets, one for the site Cart and the other for one of the site departments (catalogs) see a manual interpretation of the filled arrays below.

$catalog[] = array( 
  array('ProdID'=>2,'Name'=>'Alpha','DepID' =>2,'InBasket'=>'0'),       
  array('ProdID'=>6,'Name'=>'Alpha','DepID' =>2,'InBasket'=>'0'),
  array('ProdID'=>7,'Name'=>'Alpha','DepID' =>2,'InBasket'=>'0'),
  array('ProdID'=>8,'Name'=>'Alpha','DepID' =>2,'InBasket'=>'0'),
  array('ProdID'=>9,'Name'=>'Alpha','DepID' =>2,'InBasket'=>'0'),
);


$cart[] = array(
  array('Name'=>'Alpha2','Loc'=>'e_vol1','BasketID'=>'81','ProdID'=>'2','Quant'=>'1'),
  array('Name'=>'Beta4','Loc'=>'e_vol2','BasketID'=>'81','ProdID'=>'4','Quant'=>'1'),
  array('Name'=>'Alpha8','Loc'=>'e_vol3','BasketID'=>'81','ProdID'=>'8','Quant'=>'1'),
  array('Name'=>'Gamma21','Loc'=>'e_vol4','BasketID'=>'81','ProdID'=>'21','Quant'=>'1'),
);

What I need to do is loop through the catalog array each time a new catalog is chosen, comparing the ProdID of each row in the cart against the ProdID of each row of the catalog, when a match is found I would like to update the catalog 'InBasket' value for that row only to '1' to indicate that the item is already in the customers cart which I can then show on screen (The customer is only allowed to purchase one of any item).

There are five different departments (catalogs) which will contain up to 10 products the cart will contain say four items (If I'm lucky)

I have tried some loops but they don't seem to work.

for ($x = 0; $x < count($catalog); $x++)
{
  for ($y = 0; $y < count($cart); $y++)
  {
    If ($catalog[$x]['ProductID'] == $cart[$y]['ProductID'] )
    {
      $cart[$x]['InBasket'] = 1;
    }
  }
}

I hpoe that my arrays are correct, but, the loops seem to update 'InBasket' regardless.

Any ideas would be appreciated.

In your example, the Product ID in both tables is ProdID; you're checking 2 undefined/void array elements (which will be equal).

if ($catalog[$x]['ProdID'] == $cart[$y]['ProdID'] )

Your $cart has an array key called ProdID, but you are attempting to use ProductID which doesn't exist. Then, you are attempting to update the InBasket key of the $cart subarrays, when really, it is a member of the $catalog array.

First thing's first:

Get rid of those incremental loops. In PHP, we much more typically use foreach for iteration, which is a lot more readable:

foreach ($catalog as &$catalog_item) {
  foreach($cart as $cart_item) {
    if ($catalog_item['ProductID'] == $cart_item['ProdID']) {
       // The InBasket key is part of the catalog, not the cart!
       $catalog_item['InBasket'] = 1;
    }
  }
}

The syntax of your array example is wrong:

$catalog[] = array('whatever');

This means that the array with whatever will included into another array.

See this example: http://codepad.org/OMbnEEjA Then you'll see the difference.

Several problems:

1. you are using the wrong key name:

   If ($catalog[$x]['ProductID'] == $cart[$y]['ProductID'] )
   

change it to:

    If ($catalog[$x]['ProdID'] == $cart[$y]['ProdID'] )

1. in the second loop you are doing:

   $cart[$x]['InBasket'] = 1;
   

   but you stated in the question you would like to update the catalog, so it should be:

   $catalog[$x]['InBasket'] = 1;
   

You should use the method suggested by @jicd for looping, it is much easier.

look here for more info on how to use foreach.