Common config file for php class and use them in functions

Here's a list in order of best to worst practice

1: include and inject into class via constructor

include("config.inc.php");

$fp = new frontproduct($config);

2: include and inject via setter (the "optional dependancy" method)

include("config.inc.php");

$fp = new frontproduct();
$fp->setConfig($config);

3: pass into function calls (the "aren't objects supposed to be easier" method)

include("config.inc.php");

$fp = new frontproduct();
$fp->doSomething($config, $arg);
$fp->doSomethingElse($config, $arg1, $arg2);

4: import in class (aka the "silent dependency method")

class frontproduct{
   public function __construct(){
         include('config.inc.php');
         $this->config = $config;
   }
}    

5: static property assignment (aka the "at least its not a global" method)

 include ("config.inc.php");
 frontproduct::setConfig($config);

6: global assignment (aka the "what is scope" method)

include ("config.inc.php");
class frontproduct{
   public function doSomething(){

         global $config;
       }
   }

Try this

class frontproduct{

function fetchrange(){
ob_start();
   include('..config.php');

$val = ob_get_clean();
 return $val;
    }
}

// myfile.php

include('../config.php'); 

class frontproduct {

    function fetchrange(){


    }

}

You should include configuration file before class code, and please make sure you are understand how you should use relative paths.