multidimensional array faster than variable

[Cardale]

I am going through some information and wanted to know if a multidimensional array is faster than simply creating a variable and reassigning it with whatever added value?

 

I guess my understanding of this multidimensional array would be like two tables one with a pointer value that adds information together to form the real value.  Is this correct?

[mikesta707]

I think your idea of arrays in general is kind of skewed. In PHP multidimensional arrays are nothing more than arrays of arrays. As far as if one is faster than the other, neither is really much faster as far as storing information goes. Traversing through an array is obviously going to be slower than accessing the value of a variable...

 

 

but speed isn't really the point. Arrays are used to group related information. single variables are for any information that can't or shouldn't be grouped with other information

[Cardale]

In an array I am missing the point then because it seems that $value = $oldvalue . $newvalue; or $value['old']['new'];

 

Is the same thing?

[premiso]

In an array I am missing the point then because it seems that $value = $oldvalue . $newvalue; or $value['old']['new'];

 

Is the same thing?

 

In the first one you are just concatenating two values into $value, the other one you are accessing a single value inside a multi-dimensional array.

 

As far as speed goes, arrays will be quicker. I do not know the technical parts behind it, but I do know that you can access data in an array element faster. It is probably something to do with an array has a pre determined size (not sure in PHP but I know in like VB/C++ etc you have to pre-define the array size). So I am sure PHP buffers this size and allows for additional items to be added. Where as a variable being created creates a new spot in memory.

 

EDIT:

Well doing some reading it looks like I was wrong in my head. Anyhow there are times to use an array vs variables and using them properly will give your script the best performance.

 

Like I said I do not understand the technical part of it (I never really liked all that mumbo jumbo although I should have learned it better). But an array will access data quicker than creating a new variable. However, as mike stated, you should use the proper item for what you need, if you need to increment a variable then assigning a variable to a number is better vs holding a collection of data such as database connection info.

 

But $value = $oldvalue . $newvalue; is not the same as $value['old']['new'] Example is here:

<?php
$oldvalue = "test ";
$newvalue = " test 2";
$value = $oldvalue . $newvalue;
echo "The new value of value is: {$value}<br />";

$value = array("old" => array("new" => array("test")));

echo "The value stored in array at index of old and index of new inside old is: {$value['old']['new']}";
?>

 

Hopefully that clears it up a bit more.

[Cardale]

Is there any example of a realistic real life approch to this?  Something that is useful to give me an idea of how this would be applied?

 

Thanks.

[premiso]

Is there any example of a realistic real life approch to this?

 

Can you provide example data that you want to go through and what you would like done with it?

[Cardale]

Oh I'm sorry I don't have any exact code I am referring to.  I am simply trying to better understand the concepts.

[Cardale]

I guess I can't come up with an example because I don't understand why anyone would use a multidimensional array.

[premiso]

Ok, here is an example:

 

Say on my website I want categories with sub-categories and I want them in a multi-dimm array so I can display them with a simple loop so the array would be setup something like this:

 

<?php
$categories = array("Top Level1" => array("Sub Level1-1", "Sub Level1-2"), "Top Level2" => array("Sub Level 2-1"), "Top Level3");

foreach ($categories as $category => $subCat) {

    if (is_array($subCat)) {
	echo $category . "<br />";
         foreach ($subCat as $sub) {
              echo "  " . $sub . "<br />";
        }
    }else {
	echo $subCat . "<br />";
}
    echo "<br />";
}
?>

 

The above is a very rough and simple example, hopefully it helps you understand what you may want to use a multi-dimm array for.