add.fun.php

<?php
    header("Content-type: text/html; charset=utf-8");

    function add($min_int,$max_int)
    {
        $sum=0;
        for($i=$min_int;$i<=$max_int;$i++)
        {
            $sum=$sum+$i;
        }
        return $sum;
    }
    print_r(add(5,10));
?>