Need help abut understanding array

[handoyo]

Hi all,i found out a tutorial about ecommerce on phpwebcommerce.com..There are a some codes like this

$sql = "SELECT cat_id, cat_parent_id, cat_name
		FROM tbl_category
		ORDER BY cat_id";
$result = dbQuery($sql) or die('Cannot get Product. ' . mysql_error());

$categories = array();
while($row = dbFetchArray($result)) {
	list($id, $parentId, $name) = $row;

	if ($parentId == 0) {
		// we create a new array for each top level categories
		$categories[$id] = array('name' => $name, 'children' => array());
	//print_r($categories);
	} else {
		// the child categories are put int the parent category's array
		$categories[$parentId]['children'][] = array('id' => $id, 'name' => $name);	
	//print_r($categories);
	}
}	

// build combo box options
$list = '';
foreach ($categories as $key => $value) {
	$name     = $value['name'];
	$children = $value['children'];

	$list .= "<optgroup label=\"$name\">"; 

	foreach ($children as $child) {
		$list .= "<option value=\"{$child['id']}\"";
		if ($child['id'] == $catId) {
			$list.= " selected";
		}

		$list .= ">{$child['name']}</option>\r\n";
	}

	$list .= "</optgroup>";
}

return $list;

 

The database like this

cat_id   cat_parent_id         cat_name 	                   cat_description 	                           cat_image
17 	    13 	            Hunter X Hunter     Story about hunter and combat 	 
12         0 	                    Cars 	                Expensive and luxurious cars 	dce08605333d805106217aaab7f93b95.jpg
13 	    0 	                    Manga 	                It's all about manga, yay.... 	2a5d7eb60c1625144b3bd785bf70342c.jpg
14 	    12 	            Volvo 	                Swedish luxury car 	 
15 	    12 	            Mercedes-Benz 	Expensive but real good 	 
16        13 	            Naruto 	                This is the story of Naruto and all his gang 	 
18 	    0 	                    testing 123 	        tes

 

When i try to print_r like this

$categories[$id] = array('name' => $name, 'children' => array());
print_r($categories);

 

it gives me

Array ( [12] => Array ( [name] => Cars [children] => Array ( ) ) ) Array ( [12] => Array ( [name] => Cars [children] => Array ( ) ) [13] => Array ( [name] => Manga [children] => Array ( ) ) ) Array ( [12] => Array ( [name] => Cars [children] => Array ( [0] => Array ( [id] => 14 [name] => Volvo ) [1] => Array ( [id] => 15 [name] => Mercedes-Benz ) ) ) [13] => Array ( [name] => Manga [children] => Array ( [0] => Array ( [id] => 16 [name] => Naruto ) [1] => Array ( [id] => 17 [name] => Hunter X Hunter ) ) ) [18] => Array ( [name] => testing 123 [children] => Array ( ) ) ) 

 

and

$categories[$parentId]['children'][] = array('id' => $id, 'name' => $name);	
print_r($categories);

 

it gives me

 

Array ( [12] => Array ( [name] => Cars [children] => Array ( [0] => Array ( [id] => 14 [name] => Volvo ) ) ) [13] => Array ( [name] => Manga [children] => Array ( ) ) ) Array ( [12] => Array ( [name] => Cars [children] => Array ( [0] => Array ( [id] => 14 [name] => Volvo ) [1] => Array ( [id] => 15 [name] => Mercedes-Benz ) ) ) [13] => Array ( [name] => Manga [children] => Array ( ) ) ) Array ( [12] => Array ( [name] => Cars [children] => Array ( [0] => Array ( [id] => 14 [name] => Volvo ) [1] => Array ( [id] => 15 [name] => Mercedes-Benz ) ) ) [13] => Array ( [name] => Manga [children] => Array ( [0] => Array ( [id] => 16 [name] => Naruto ) ) ) ) Array ( [12] => Array ( [name] => Cars [children] => Array ( [0] => Array ( [id] => 14 [name] => Volvo ) [1] => Array ( [id] => 15 [name] => Mercedes-Benz ) ) ) [13] => Array ( [name] => Manga [children] => Array ( [0] => Array ( [id] => 16 [name] => Naruto ) [1] => Array ( [id] => 17 [name] => Hunter X Hunter ) ) ) ) 

 

1.How should i format the output so i can learn the results that was returned?

2.What does

   

$categories[$id] = array('name' => $name, 'children' => array());

    and

   

$categories[$parentId]['children'][] = array('id' => $id, 'name' => $name);

means?

3.What is the uses of .= ?

 

Thanks a lot...God bless you all..

[marvelade]

1) For a more readable output do this instead:

 

echo '<pre>' . print_r($result,true) . '</pre>';

 

2) When you've completed a tutorial on how associative arrays work you will understand. there's tons of explanations on the internet far better than waht I can explain here

 

3) .= means you glue a string to another variable

 

$a = "Hello";
$a.= " Moon";

echo $a; // this will output "Hello Moon".

 

actually this:

 

$a .= " Moon";

 

does the same as

$a = $a . " Moon";

 

but it's a little shorter to write.

 

greetz,

Marv