PHP require Statement

The require statement in PHP includes and executes a specified file. Unlike the include statement, if the required file is not found, PHP produces a fatal error and terminates the script execution.

Syntax

require "filename.php";
// or
require("filename.php");

How require Works

PHP searches for the file in the current directory first, then in directories specified in the include_path setting of php.ini. If the file is not found, PHP emits an E_COMPILE_ERROR and halts execution.

Example

Here's a simple example showing how require includes a file ?

<?php
echo "Main script started<br>";
$mainVar = 100;

// This would normally require an external file
// For demo purposes, we'll simulate the behavior
echo "Simulating require 'external.php'<br>";

// Code that would be in external.php:
$externalVar = 200;
echo "Sum: " . ($mainVar + $externalVar) . "<br>";
echo "Main script continues<br>";
?>

Main script started
Simulating require 'external.php'
Sum: 300
Main script continues

Error Handling

When a required file is not found, PHP generates a fatal error ?

<?php
echo "Script started<br>";
require "nonexistent.php";  // This file doesn't exist
echo "This line won't execute<br>";
?>

This produces a fatal error:

Script started
PHP Fatal error: require(): Failed opening required 'nonexistent.php'

require vs include Comparison

Conclusion

Use require for essential files that your script cannot function without. The fatal error behavior ensures your application doesn't run with missing dependencies.