How to "reset/unset" array with string keys

[ywickham]

Hello everyone, and thank you to all who have helped me get this far! 🙂

Short version of my problem:
How do I clear an array that uses string keys, or a combo of string and numeric keys without having to list each array element individually?

Long version of my problem:
I have two arrays (gen_array[][], gen2_array[]), both in a loop, one setup to use string keys the other a combo of string/numeric keys. My first time through the loop, the data printed from the arrays is exactly as it should be. The second time through the loop, I get garbage: mis-matched array elements (as one of these arrays references the other) and duplicates of items already processed.

I figured out that this is due to not clearing out the array (or so I think.) So I searched the manual and found unset().

Unset works but seems to leave the keys in the array (releaving me of the "duplicates" problem, but not of the mismatched arrays issue), as my second list doesn't start until after the last element created from the first time through the loop, i.e. a sample list:

1st time thru loop -
element 1: value 1
element 2: value 2
element 3: value 3

2nd time thru loop -
element 1:
element 2:
element 3:
element 4: value 1
element 5: value 2

How can I clear out my arrays for use again?

Thanks!

[metin]

I'm not sure that understand what exactly is your problem!
But why don't you reset the internal pointers of the arrays
after the first loop?
Like:

// first loop here
reset($array1);
reset($array2);
// second loop here

[ywickham]

I've actually tried reset and it is is not working as it should in that instead of rewinding back to the first element of the array and letting me overwrite it and the key, it is appending to the array.

Other ideas, anyone?

[Weedpacket]

Still not clear what your problem is (not enough solid detail) - how are you trying to write to the array? If it's just $array[]=$something, then the behaviour you describe would be expected.

[ywickham]

Here's a snippet of the code. When I go through the counter loop the second time, the $gen2_array gets appended to, instead of overwritten.

If I use reset(), the second set of data is appended to the end of the array.

If I use unset(), on the second loop, the $gen2_array array elements are erased, but the indexes remain, so their are as many empty elements at the beginning of the array as the number of elements created when running through the loop the first time.

I apologize if I'm making this more difficult than it needs to be...just having a hard time explaining it.

<?
$array_ctr = 0;
$first_manu = 1;
$counter = 0;


for ($counter = 1;$counter < 3; $counter++) {


if ($counter == 1){ /*first time thru listing cameras*/
	$current = 'Yes';
	$section_title = "Currently Manufactured";
	$marker = "current";
} else { /*not first time thru camera listing*/
	$current = 'No';
	$section_title = "Discontinued Cameras";
	$marker = "dis";
}


/*Send query*/
$query = "SELECT camera_id, manufacturer_name, model_name, review_url, review_date
FROM camera_general
WHERE review_date != '0000-00-00'
ORDER BY model_name";

$result = mysql_query($query) or die(mysql_error());

//Load array
while ($rst = mysql_fetch_array($result)) {

	$gen_array[$array_ctr][camera_id] = $rst[camera_id];
	$gen_array[$array_ctr][manufacturer_name] = $rst[manufacturer_name];
	$gen_array[$array_ctr][model_name] = $rst[model_name];
	$gen_array[$array_ctr][review_url] = $rst[review_url];
	$gen_array[$array_ctr][review_date] = $rst[review_date];
	$array_ctr++;
}


//Load model_name in seperate array to run natsort
$v=0;
while ($v < $array_ctr) {

	$gen2_array[] = $gen_array[$v][model_name];
	$v++;
}

natsort($gen2_array);

/*Print digicam pages by linking to original array by key*/
foreach($gen2_array as $key => $cam_name) {

	if ($first_manu) {

		/*Save comparison variable for later use*/
		$current_manu = $gen_array[$key][manufacturer_name];

		/*Reset first manufacturer variable to false*/
		$first_manu = 0;

		/*Set printing variable to true for printing manufacturer row*/
		$print_manu_row = 1;
	} else {

		/*Do this if the current manufacturer is not the same as the stored variable*/
		if ($current_manu != $gen_array[$key][manufacturer_name]) {

			/*Set section header to correct type*/
			$current_manu = $gen_array[$key][manufacturer_name];

			/*Set printing variable to true for printing manufacturer row*/
			$print_manu_row = 1;
		}
	}

	if ($print_manu_row) { ?>

		<tr><td>&nbsp;</td></tr>
		<tr>
			<td colspan="2"><b><?=$current_manu; ?></b></td>
		</tr>
		<? 	/*Reset variable to turn off manufacturer row printing*/
		$print_manu_row = 0;
	}
?>
  <tr>
	<td><b><?=$cam_name; ?></b></td>
	<td>
<?
		//Print review url link
		$review_url = $gen_array[$key][review_url];
		print("<a href=\"$review_url\">Review</a> ");
?>
		</td>
	  </tr>
<?
	} // match for: foreach

} //match for: for counter

$first_manu = 1;
?>

[Weedpacket]

A replacement for the bit of code between the mysql_query() and the natsort() lines (inclusive):

$result = mysql_query($query) or die(mysql_error());
$array_cnt = mysql_num_rows($result);

// Clear arrays from last query.
unset($gen_array, $gen2_array);
//Load array
for($i=0; $i<$array_cnt; ++$i) {
	$gen_array[] = mysql_fetch_array($result);
}
//Load model_name in seperate array to run natsort
for ($v=0; $v < $array_cnt; ++$v) {

$gen2_array[$v] = $gen_array[$v]['model_name'];
}

natsort($gen2_array);

Obviously, I haven't tested it, but the crucial thing to notice is that I unset() the arrays entirely, since you don't want data from previous iterations contaminating the current one.

[ywickham]

Thank you. Your code actually works perfectly. It looks like I was going about it the wrong way...unsetting in the wrong place (when I did it) and loading the array the hard way.

Thank you so much! I am very grateful.

[Weedpacket]

Another thing I haven't tried is ditching the gen2 array completely, and just sorting the gen array directly:

function order_by_model_name($a,$b)
{   return strnatcmp($a['model_name'], $b['model_name']);
}

//...
usort($gen_array, 'order_by_model_name');

All right, I'll be honest - I only just remembered strnatcmp. I figured, since natsort is there, an analogous comparison function would be a sensible thing to have...

[ywickham]

That works too. (Just tested it.) I may end up going that route, so that I don't have to work with two arrays...