CREATING
ARRAYS
The
formally defined way to create an array in PHP code is
to use array(). Although array() looks like a function
it is a language construct, like echo().
It's
probably best to start with the most formal syntax.
There
are other ways to code the task but these are less explicit.
SIMPLE,
INDEXED LIST
To
begin with we will use array() to create
an array of a version the shopping list we looked
at earlier
| |
bread |
| |
lemonade |
| |
apples |
| |
potatoes |
| |
coffee |
|
we
can use array() to assign values to a simple
indexed array using
$shoppinglist
= array("bread", "lemonade",
"apples", "potatoes", "coffee");
where
bread will have the index 0 (zero, that is), lemonade
1, apples 2, grapes 3 and coffee 4.
Notice
the we would get exactly the same result using slightly
different code:
$shoppinglist
= array(0 => "bread",
1 => "lemonade",
2 => "apples",
3 => "potatoes",
4 => "coffee");
Here
it is more obvious how the indices are applied to the
elements we're storing in the array. Notice, also, that
placing different parts of the text on different lines
doesn't affect the function but it does make
the text easier to read.
Having
the option to specify the key like this gives us an insite
into how more complex keys can be used in creating an
associative array. |
Numbering
indices
Notice
that indices of PHP arrays start at zero, not one.
This is a common concept in processing lists and
strings in most programming languages.
In
PHP the same principle is applied to string processing,
where the first character in a string is character
zero - In the string Rock and Roll, the
character R appears in positions 0 and 9, l appears
in positions 11 and 12 and the string is 13 characters
long.
|
 |
|
We
could, for instance, categorise our shopping list in
the array $shoppinglist like this
$shoppinglist
= array("bakery" => "bread",
"drink" => "lemonade",
"fruit" => "apples",
"vegetables" => "potatoes",
"beverage" => "coffee");
In
this instance the keys and their associated values would
be
| Key |
Value |
| bakery |
bread |
| drink |
lemonade |
| fruit |
apples |
| vegetables |
potatoes |
| beverage |
coffee |
As
a final step before we look at getting elements out of
arrays and actually using them for something, we can
code the shopping list into a PHP web page:
|
|
| Open a new document in your HTML editor, calling
it shopping.php |
 |
| Start by creating the HTML page framework, starting
with the HTML tag pair and creating a head and body
for the document |
<head>
<
title>A shopping list</title>
< /head>
<body>
</body>
< /html>
|
| Add
a line of text and then the code to initialise the
shopping list array |
<head>
<
title>A shopping list</title>
< /head>
<body>
The shopping list<BR>
< ?PHP
$shoppinglist = array("bread", "lemonade",
"apples", "potatoes", "coffee");
?>
</body>
< /html>
|
| Save the file |
|
| Just to see what happens, add a print to the PHP
code |
<head>
<
title>A shopping list</title>
< /head>
<body>
The shopping list<BR>
< ?PHP
$shoppinglist = array("bread", "lemonade",
"apples", "potatoes", "coffee");
print("The list array is $shoppinglist<BR>\n");
?>
</body>
< /html> |
Save the file and look at it in a browser (You'll
need to access the page through a web server to process
the PHP: Use the format http://localhost/shopping.php
and not a physical path like C:\intepub\shopping.php)
Here's one I prepared earlier: shopping.php
Which may whet your appetite for the next page:
Accessing arrays |
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