PHP, Arrays for beginners

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» Arrays for beginners
by Mike Milano

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Breaking it down, Key and Value

Breaking it down, Key and Value

PHP Code:


			
$fruit = array('apple', 'orange', 'pear');

Here is our fruit example once again. Each item in an array is automatically assigned a number, or key. When working with arrays in PHP, numbering always starts with 0.

I am going to create the same array I have in the above example manually.

PHP Code:


			
$fruit[0] = 'apple';

$fruit[1] = 'orange';

$fruit[2] = 'pear';

The 'key' is what is between the brackets, and the value is to the right of the equal sign.

Here is an example how you could iterate through this array by increasing the key by 1 in a simple for() loop.

PHP Code:


			
$count = count($fruit);

for ($i=0;$i<$count;$i++) {

  echo $fruit[$i] . "<br>";

}

Other types of keys

Get ready for this. Keys can be letters also. Let's scrap the fruit example for now. We're going to make a person array. This won't be an array of people, but an array of one person's attributes. I'll demonstrate creating this array using the 2 different methods I did with the fruit.

PHP Code:


			
// create the array all in one

$person = array(

        'first_name' => 'John', 

        'last_name' => 'Smith',

        'username' => 'jsmith'

        );



// or create it one attribute at a time

$person['first_name'] = 'John';

$person['last_name'] = 'Smith';

$person['username'] = 'jsmith';

Now our $person variable contains the attributes of a person and we are using the key to specify the type of attribute.

Ready for a real-world example? In this example I'm going to query an imaginary database for all my users and return an array of people.

PHP Code:


			
function getPeople() {

  // initialize people array

  $people = array();



  // query database ( assume i already have a connection )

  $result = mysql_query("select first_name, last_name, username from users");

  // iterate through results

  while ($row = mysql_fetch_assoc($result)) {

    // initialize a person array

    $person = array();

    $person['first_name'] = $row['first_name'];

    $person['last_name'] = $row['last_name'];

    $person['username'] = $row['username'];



    // append people array

    $people[] = $person;

  }



  return $people;

}

You can see how I'm getting the value from $row the same way I'm assigning it to $person. This is because mysql_fetch_assoc gets an array from the database. You could actually replace those 4 lines that begin with $person with $person = $row, but I wanted to demonstrate the long way for easier understanding.

Now look at the line below the comment: // append people array. We just created a $person array, and we are putting that into the $people array. This is called a Multi-Dimensional Array.

It's a pretty intimidating word, but doesn't what we just did make sense? I'll elaborate on the next page.

(printer friendly format)

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