how to importing a php file to another file code example

Example 1: include and require in php

// Include a file, if it can't be found: continue.
<?php
include 'mainfile.php';
?>
  
// Alternatively: Require a file to be imported or quit if it can't be found
<?php
 require 'requiredfile.php';
?>

Example 2: php import script

include 'docName.php';