Variables from outside PHP

HTML Forms (GET and POST)

IMAGE SUBMIT variable names

When submitting a form, it is possible to use an image instead of the standard submit button with a tag like:

<input type=image src="image.gif" name="sub">

When the user clicks somewhere on the image, the accompanying form will be transmitted to the server with two additional variables, sub_x and sub_y. These contain the coordinates of the user click within the image. The experienced may note that the actual variable names sent by the browser contains a period rather than an underscore, but PHP converts the period to an underscore automatically.

HTTP Cookies

PHP transparently supports HTTP cookies as defined by Netscape's Spec. Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users. You can set cookies using the SetCookie() function. Cookies are part of the HTTP header, so the SetCookie function must be called before any output is sent to the browser. This is the same restriction as for the Header() function. Any cookies sent to you from the client will automatically be turned into a PHP variable just like GET and POST method data.

If you wish to assign multiple values to a single cookie, just add [] to the cookie name. For example:

SetCookie("MyCookie[]","Testing", time()+3600);
     

Note that a cookie will replace a previous cookie by the same name in your browser unless the path or domain is different. So, for a shopping cart application you may want to keep a counter and pass this along. i.e.

$Count++;
SetCookie("Count",$Count, time()+3600);
SetCookie("Cart[$Count]",$item, time()+3600);
     

Environment variables

PHP automatically makes environment variables available as normal PHP variables.

echo $HOME;  /* Shows the HOME environment variable, if set. */
    

Server configuration directives