PHP Control Structures include & require
Example
require
require is similar to include, except that it will produce a fatal E_COMPILE_ERROR level error on failure. When the require fails, it will halt the script. When the include fails, it will not halt the script and only emit E_WARNING.
require 'file.php';
PHP Manual - Control Structures - Require
include
The include statement includes and evaluates a file.
./variables.php
$a = 'Hello World!';
./main.php`
include 'variables.php';
echo $a;
// Output: `Hello World!`
Be careful with this approach, since it is considered a code smell, because the included file is altering amount and content of the defined variables in the given scope.
You can also include file, which returns a value. This is extremely useful for handling configuration arrays:
configuration.php
<?php
return [
'dbname' => 'my db',
'user' => 'admin',
'pass' => 'password',
];
main.php
<?php
$config = include 'configuration.php';
This approach will prevent the included file from polluting your current scope with changed or added variables.
PHP Manual - Control Structures - Include
include & require can also be used to assign values to a variable when returned something by file.
Example :
include1.php file :
<?php
$a = "This is to be returned";
return $a;
?>
index.php file :
$value = include 'include1.php';
// Here, $value = "This is to be returned"
