Difference between include and include_once in php
Using include, you can tell PHP to fetch a particular file and load all its contents. It’s as if you pasted the included file into the current file at the insertion point.
include vs include_once
Including a PHP File
<?php include "somewhat.php"; // Your code goes here ?>
include_once in php
Using include_once
Each time you issue the include directive, it includes the requested file again, even if you’ve already inserted it.
Let YourFile.php
contains a lot of useful functions, so you include it in your file, but you also include another library that includes YourFile.php
.
Through nesting,You include twice.This will produce error messages, because you’re trying to define the same constant or function multiple times. So, you should use include_once
instead.
<?php include_once "yourFile.php"; // Your code goes here ?>
include vs require in php
A potential problem with include
and include_once
is that PHP will only attempt to include the requested file. Program execution continues even if the file is not found.
require_once in php
When it is absolutely essential to include a file, require it. For the same reasons I gave for using include_once
, I recommend that you generally stick with require_once
whenever you need to require a file.
<?php require_once "yourFile.php"; // Your code goes here ?>