PhP variable declared in a loop and I would like to store it in a global array

Question

Im new to PHP and would like to get some advice on the following situation:

I have a file in which Im parse an XML file. My strategy has been create a "parser.php" file. Then create separate files for each tag in the XML file. Each of these separate files is a class that when instantiated will store all the attributes of that particular tag.

I have several loops in the parser that instantiate the class that corresponds with the tag when they encounter it.Once the loop is done that object is then inserted into a global array.

Here is the code:

<?php
include ('class.Food.php');
include ('class.Drink.php');
$xml = simplexml_load_file("serializedData.xml");

//Global Variables==============================================================

$FoodArray = array();
$DrinkArray = array();
$FoodObj;
$DrinkObj;

foreach($xml->children() as $child)
{
//Instantiate a Food object here and insert into the array
$FoodObj = new Food();
//Add attributes of tag to the Food object
array_push($FoodArray, $FoodObj);

}

Thus at the end of each loop there would be a food object created and that would be added to the FoodArray.

My questions are:

Do I have to explicitly call a destructor or free the object memory at the end of the loop?
Using the above syntax, will the FoodObj be stored in the FoodArray as a reference or a value
Each time the variable Food gets a different instance stored in it, does that matter when stored in the array? All the objects stored in the array go by the index number right?

Thanks

Marc B · Accepted Answer · 2011-07-19 19:10:41Z

1

If you 'free' the Food() object at the end of the loop, you'd be killing the last reference to it you pushed into $FoodArray as well. PHP will clean up for you and delete things when they go out of scope. Since you're assigning to a global array, the scope is the whole script. So unless you explicitly take steps to delete an item from $FoodArray, the objects will be kept around until the script exits.
http://www.php.net/manual/en/language.oop5.references.php
array_push puts elements onto the end of the array, so they'll get an incrementing index number.

answered Jul 19, 2011 at 19:10

Marc B

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Comments

Mr Griever · Accepted Answer · 2011-07-19 19:12:58Z

0

Try the following

$FoodArray = array();
$DrinkArray = array();

foreach($xml->children() as $child) 
{
    //Instantiate a Food object here and insert into the array 
    $FoodObj = new Food(); 
    //Add attributes of tag to the Food object 
    $FoodArray[] = $FoodObj;
    unset($FoodObj);
}

1) unset'ng the instance manually is good form, but unnecessary. the php garbage collector will do it for you anyways and is very efficient.

2) in the example above, $FoodArray[i] will continue to point to the instance even after $FoodObj is unset.

3) it works whether $FoodObj is local to the loop or not. But for best practice it should be.

answered Jul 19, 2011 at 19:12

Mr Griever

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2 Comments

banditKing Over a year ago

So does a copy of the FoodObj get inserted into the array or is it a reference to the FoodObj that gets inserted into the array?

Mr Griever Over a year ago

a copy. you can see the original is unset, but the array still contains the object instance.

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