PHP cant use variable defined outside functions
Question by Adonis K.
Im working on a project (simple xml CMS) just to learn some basic PHP.
first i include a config.php file which contains information about the CMS, then i include a route.php for the url routing and after that i include a functions.php file which is pretty similar to the wordpress’ one (contains all the functions to for example load posts, tags, categories etc).
The structure looks like this:
function products($search = FALSE, $query= '', $page = 1, $results = 5){
}
function getProductById($id){
}
function getProductTitleById($id){
}
function getProductByExcerpt($excerpt){
}
function getProductTitleByExcerpt($excerpt){
}
function getPost($id, $title, $description, $category, $excerpt = FALSE){
}
function getTitle(){
}
function breadcrumb($params, $first){
}
function pagination($page, $pages){
}
?>
In config.php file i also use this code:
$xml = simplexml_load_file('products.xml') or die('The Product xml file couldnt be loaded.');
But when i try to access $xml from within the functions i prepared in functions.php, i get a undefined variable notice. (i also tried placing the $xml variable inside the functions.php before the definition of the functions but got the same result).
Can someone please tell me my mistake? I know its simple, i just cant see clearly right now.
Thanks in advance.
Answer by Another Code
You have a scoping issue. The variables declared in the global scope aren’t visible inside your functions. The manual explains what you can do about it. An overview:
- Import the variable from the global scope into the local scope of your function with
global $xml;at the start of the function - Store the variable as a key of the global variables superglobal, i.e.
$GLOBALS['xml'] - Make the variable a static member of a class or create a singleton construction
- Pass the variable as an argument to every function that needs it
Note that when using a good OOP-style architecture these kind of problems can often be avoided, e.g. $xml would be a property of class instances that need direct access to the DOM object.
Answer by Starx
Functions or methods do not have scopes outside them. In order to use a variable declared outside. Using global keyword, to tell the server to use the variable defined in higher scope.
$varname = "value";
function yourfunctionname() {
//In order to use the variable declare you want to use the globally declared
global $varname;
//now $varname will have "value` as its value
//continue with your logic
}
