Recipe 9.10 Handling Remote Variables with Periods in Their Names
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.
9.10.4 See Also
Documentation on variables from outside PHP at
http://www.php.net/language.variables.external.php.
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