Arrays and PHP: A Primer - Arrays and their uses

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Before we continue, you should understand that an array is simply a value stored in memory with more than one segment of allocation, meaning that one variable can "store" more than one value. Each value is indexed either numerically, or by a text reference. Here's an example:

<?

$Arthur[0] = "Value01";

$Arthur[1] = "Value02";

$Arthur[2] = "Value03";

$Arthur[3] = "Value04";

$Arthur[4] = "Value05";

?>

As you can see from the example above, the $Arthur variable is now an array, and can take five values, which are indexed from 0 to 4. Here's an idea of how the $Arthur variable would look in memory:



The address of the $Arthur variable is the address of the first index, 0. The address of each index after that is calculated as the address of the previous index, plus the size of the data type being stored. For example, if $Arthur[0] has the address of 0x19DA00 and the $Arthur array was storing only integers (4 bytes), then the address of $Arthur[1] would be 0x19DA04.

To print out the values stored in the $Arthur array, we would use this snippet of code:

<?

$arthur[0] = "Get Value 01";

$arthur[1] = "Get Value 02";

$arthur[2] = "Get Value 03";

$arthur[3] = "Get Value 04";

$arthur[4] = "Get Value 05";

for($i = 0; $i < 5; $i++) {

print $arthur[$i] . "<br>";

}

?>

The print command will output each of the values to our browser, as shown below:



There are many different ways that we can declare both single and multi-dimensional arrays in PHP. Let's look at some of them now.

Next: Single dimension arrays >>
 

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