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
Each time you issue the include directive, it includes the requested file again, even if you’ve already inserted it.
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
<?php include_once "yourFile.php"; // Your code goes here ?>
include vs require in php
A potential problem with
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 ?>