Functions stop working when file included with root path (leading slash)

My PHP files in my root directory INCLUDE header.php. Header.php INCLUDEs functions.php. I’m adding new pages in a subdirectory, so I added leading slashes to all my links in header.php: CSS, menu items and the subsequent INCLUDE to functions.php. The CSS and menu items work fine on this page in the subdirectory, but the functions don’t work. There are no links in the functions that seem to need leading slashes.

Does the combination of include and leading slashes require modifying functions?

From a page in the root directory:

include('header.php');

From a page in the subdirectory:

include('/header.php');

From header.php:

include('/functions.php');

And the function that no longer works (called from pages in the root directory or subdirectory):

function show_date($array_name){
if (date("Y F j",strtotime($array_name["exhibit_open"])) == date("Y F j",strtotime($array_name["exhibit_close"]))){
    echo date("F j, Y",strtotime($array_name["exhibit_open"]));
}
elseif (date("Y",strtotime($array_name["exhibit_open"])) != date("Y",strtotime($array_name["exhibit_close"]))) {
    $first_date_format = "F j, Y";
    echo date($first_date_format,strtotime($array_name["exhibit_open"])). " - ". date("F j, Y",strtotime($array_name["exhibit_close"]));
} elseif (date("F",strtotime($array_name["exhibit_open"])) != date("F",strtotime($array_name["exhibit_close"]))){
    $first_date_format = "F j";
    echo date($first_date_format,strtotime($array_name["exhibit_open"])). " - ". date("F j, Y",strtotime($array_name["exhibit_close"]));
} else {
    $first_date_format = "j";
    echo date("F j",strtotime($array_name["exhibit_open"])). " - ". date($first_date_format,strtotime($array_name["exhibit_close"])). ", ". date("Y",strtotime($array_name["exhibit_close"]));
}

}

Standard Paths 101:

/path/somefile – the leading / anchors this path structure at the ROOT of the file system, e.g. it’s the equivalent of C:pathsomefile.

path/somefile – no leading /. The OS will use the programs “current working” directory as the basis of the path, so if you’re in a shell that’s in /home/foo, then somefile will be search for in /home/foo/path/somefile.

../somefile. the .. refers to the PARENT directory of the current working directory, so if you’re in /home/foo, then ../somefile will be searched for as /home/somefile.

Note that you can have non-sensical paths like

/../../../../somefile. This will be acceptable, but is pointless, as you’re both anchoring the path at the root of the file system, then trying to go ABOVE the root, which is not possible. This path is the operational equivalent of /somefile.

Just so you’re aware, if you’re going to have the php pages you’re requesting also request other pages themselves, it may be beneficial to use require_once instead of include. That will make it so none of the pages that are included repeat themselves and you don’t have to worry about accidentally including something more than once.

That being said… when you request a page in the root directory, it will request header.php in the root directory which will in turn request functions.php in the root directory. However, if you request from the subdirectory, ../header.php will reference header.php in the root directory, but that whole file will get included, and then its the php page in the subdirectory that ends up trying to include /functions.php. It would need to request ../functions.php, but that would cause everything in the root directory to stop working.

I’d suggest setting a variable in header.php along the lines of $root = $_SERVER['DOCUMENT_ROOT']; Then, all includes in header.php should be like include($root."/functions.php");

$_SERVER['DOCUMENT_ROOT'] will get you objective url to the root, which will enable you to make sure you’re referencing the correct place no matter where you’re requesting header.php from.

Include and Require literally pull the code into the executing file, so one thing to watch out for is that the files in a subdirectory are running from the working directory.

Example:

         |-templates-|-header.php
Docroot--|
         |-inc-|-functions.php
         |
         |-index.php

Index.php

<?php
include 'template/header.php';
...
?>

template/header.php

<?php
include 'inc/functions.php';
...
?>

because the header.php code is being executed from the docroot due to the include.