将文档根目录定义为ROOT_PATH

Question

I use some constants to define paths to specific directories on a website that I'm building, like this:

define("ROOT_PATH", "http://website.com/");
define("IMAGES_DIR", ROOT_PATH . "images/");

and I usually use them like this:

echo "<img src='" . IMAGES_DIR . "some_image.jpg' />";

now I want to know if there is any difference between

define("ROOT_PATH", "http://website.com/");

and

define("ROOT_PATH", "/home/username/public_html/");

and which one of them should I use? And why?

Answer 1

You can't really use the following:

define("ROOT_PATH", "/home/username/public_html/");

since it will try to load

http://website.com/home/username/public_html/image.png

which you don't really want.

Using

define("ROOT_PATH", "http://website.com/");

will try to fetch

http://website.com/image.png

which is what you want.

Answer 2

the difference is that html won't recognize full paths on images or src attributes... but you can use this

define ('ROOT', dirname(dirname(__FILE__)));
define ('ROOT_PATH', "http://website.com/");
define ('INCLUDES',ROOT .'path/to/php/includes/'); //for php includes

Or you can use a php function to convert "ROOT_PATH" based on the getenv("SCRIPT_NAME")

Answer 3

You should use

define("ROOT_PATH", "http://website.com/");

If you use:

define("ROOT_PATH", "http://website.com/");

In client side,The image src:

http://website.com/some_image.jpg

If you use:( Just for local file system )

define("ROOT_PATH", "/home/username/public_html/");

The image src:

http://website.com/home/username/public_html/some_image.jpg