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Excerpted from Chapter 4: Interacting with Web Forms in the PHP Phrasebook by Christian Wenz. ISBN 0672328178, Copyright © 2005. Used with the permission of Sams Publishing.

When it comes to prefilling form elements, multiple
selection lists are the most difficult ones to implement.
This is because in $_GET or $_POST, you have an array
of chosen options; so you cannot just compare strings,
but you have to search for the specified value in the
array. Luckily, PHP offers something suitable in the
form of the in_array() function. So, the effort required
is not much more than with the other form elements:
If the current value is in $_GET/$_POST, print out the
selected attribute.

However, the HTML form must be specially preparedto allow PHP to access the data from the multiple
selection list:The value of the name attribute has to
end with [], hinting to PHP that it should expect an
array of values, not just a string value. Accessing the list
data, however, can still be done using $_GET[‘listname‘]/$_POST[‘listname‘] and not
$_GET[‘listname[]‘]/$_POST[‘listname[]‘], as shown
in the preceding code.
getFormData.inc.php from the previous phrases.
It contains two additional functions that return an array instead of a string.

These functions return an array for multiple lists that
you can use as you did in select-multiple.php.


Graphical Submit buttons (<input type=”image” />) are
not only a nice way to spicen up the layout of the
form, but they also offer a nice feature:The browser
submits the x and the y coordinates of the mouse
pointer when clicking on the button. In PHP, this happens
by appending _x and _y to the name attribute of
the button and writing this into $_GET or $_POST.The
preceding code evaluates this information.


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Created: March 27, 2003
Revised: January 23, 2006
URL: http://webreference.com/programming/php_forms2/1