Open
selectgoods.php and create a form on the page,
as shown on the right (Only code for the document
body is shown here)
As
you can see this is a fairly straightforward
HTML form except that, instead of giving each
of the form's text boxes a name like bakery or
drinks, we have assigned an element of an associative
array as the textbox object's name.
When
the form is submitted (clicking on the form's
submit button) the form data will be posted
to the named page: shopper.php
Save
the file to selectgoods.php and
browse to it to check it out (At this stage,
if you click on Submit the shopper.php page will
load but it should be blank) |
<body>
<
form name="frmGoods"
id="frmGoods" method="post"
action="shopper.php">
<p>Please select your shopping by naming goods in each category</p>
<p>Bakery
<input name="Array[bakery]" type="text" id="bakery" />
</p>
<p>Drinks
<input name="Array[drinks]" type="text" id="drinks" />
</p>
<p>Fruit
<input name="Array[fruit]" type="text" id="Fruit" />
</p>
<p>Vegetables
<input name="Array[veggies]" type="text" id="Veggies" />
</p>
<p>
<input type="submit" name="Submit" value="Submit" />
</p>
</form>
</body> |
Next,
open shopper.php for editing and add the code
shown to the right. This page shows a brief
introductory line of text, outputs the posted information
from selectgoods.php, then signs off with a jolly
marketing message
With
the text and code in place between the <body> tags,
save shopper.php |
<body>
<p>We have received your shopping list and
will meet your requirements as follows</p>
<p>
<?PHP
while (list($index, $item) = each($Array)) {
print("$index - $item<BR>\n");
}
?>
</p>
<p> Thank you for shopping with NonExistent Web Shops </p>
</body> |
Browse
to selectgoods.php and enter your shopping requirements,
as requested
Then
click on Submit: shopper.php should now load,
accepting the passed information from the form
|
 |
Through
HTTP shopper.php has accepted Array from selectgoods.php
and, in the while() loop has sent the category
name (the element's key) and the product type
(the element's value) to the browser.
In
the next example we'll see how an element can
be added to the array.
In
this scenario the online shop adds a free
gift to every shopper's list of requirements |
 |
Open
shopper.php for editing and amend the PHP code,
as shown
Notice
that the key to an associative array can contain
any characters, even spaces - Once the key is
named and the element assigned a value it is
created within the array, producing the output to
the browser as shown below, right
Save
the updated shopper.php file and browse to selectgoods.php and try it out |
<body>
<
p>We have received your shopping list and will
meet your requirements as follows</p>
< p>
< ?PHP
$Array["free gift"] = "PHP wallchart";
while (list($index, $item) = each($Array)) {
print("$index - $item<BR>\n");
}
?>
< /p>
<
p> Thank you for shopping with NonExistent Web Shops </p>
< /body> |
| |
 |
Next
we'll use unset() to remove an element from an
array.
In
this scenario, we know the online store will
never supply alcoholic beverages so we check
that beer isn't ordered in the drinks
category.
Open
shopper.php for editing again and make the
changes shown - Notice that we loop through the
array removing any offending requirements the
use reset() to
place the array pointer back to the first element.
If we didn't do this we'd enter the second
while() loop
still pointing at the end of the array and the
second loop would create no output. |
<?PHP
while (list($index, $item) = each($Array)) {
if ($item == "Beer") {
unset($Array[$index]);
print("Please note that we cannot supply alcoholic beverages<BR>Your
amended list is<BR>");
}
}
reset($Array);
$Array["free gift"] = "PHP wallchart";
while (list($index, $item) = each($Array)) {
print("$index - $item<BR>\n");
}
?> |
| Some
other useful array functions are shown here |
| each |
Moves
the pointer to the next array element (we've
already used this one) |
| current() |
Returns the element currently pointed to |
| reset() |
Returns the pointer to the first element |
| end() |
Sets the pointer to the last element |
| next() |
Moves the pointer on by one element |
| prev() |
Moves the pointer back one place |
| array_walk() |
Applies the same action the every member
of an array |
|
| With
the changes in place save shopper.php and browse
to selectgoods.php - Enter the same old list
and you will get the same old response. |
|
| But
change your drinks requirement to Beer and see
what the result is. |
|
One
point to note is that unset() does,
quite literally, remove the specified element
from an array. It does nothing to close up the
hole a deletion might make in the index sequence.
Notice,
then, the output produced when unset() is
used on a numerically indexed array - The first
loop outputs the contents of the array, the
second loop outputs the amended array: The results
are quite logical because PHP treats all array
keys in the same way, whether they are integer
numbers of complicated strings. Bear in mind,
too, that when using a counted loop (like a for() loop)
removing an element will change the element count.
This
is demonstrated in the page unsetdemo.php |
This
will always output the whole array without
errors because it steps sequentially through
the array
It
can be used on associative arrays as well
as numerically index arrays |
while (list($index, $item) = each($Array))
{
print("$index - $item<BR>\n");
} |
This
for() loop will encounter an error is an
element is removed from a numerically indexed
array.
It
can't be used on associative arrays |
$elementcount = count($Array);
for ($i = 0; $i < $elementcount; $i++) {
print("$i - $Array[$i]<BR>\n");
} |
|
|
|
