9.10.1 Problem
You want to process a variable with a period in its name, but
when a form is submitted, you can't find the variable.
9.10.2 Solution
Replace the period in the variable's name
with an underscore. For example, if you have a form input element named
foo.bar, you access it inside PHP as the variable
$_REQUEST['foo_bar'].
9.10.3 Discussion
Because PHP uses the period as a string concatenation operator,
a form variable called animal.height is automatically converted to
animal_height, which avoids creating an ambiguity for the parser. While
$_REQUEST['animal.height'] lacks these ambiguities, for legacy and
consistency reasons, this happens regardless of your register_globals
settings.
You usually deal with automatic variable name conversion when
you process an image used to submit a form. For instance: you have a street map
showing the location of your stores, and you want people to click on one for
additional information. Here's an example:
<input type="image" name="locations" src="locations.gif">
When a user clicks on the image, the x and y coordinates are
submitted as locations.x and locations.y. So, in PHP, to find
where a user clicked, you need to check $_REQUEST['locations_x'] and
$_REQUEST['locations_y'].
It's possible, through a series of manipulations, to create a
variable inside PHP with a period:
${"a.b"} = 123; // forced coercion using {}
$var = "c.d"; // indirect variable naming
$$var = 456;
print ${"a.b"} . "\n";
print $$var . "\n";
123
456
This is generally frowned on because of the awkward syntax.
