using args[] to tell which server?

I want to run my app either on the remote server or my localhost. To start it on my localhost I start the Apache and then type localhost in the browser window.  To start it on the server I type 54.152.xxx.9/sub_crud on the browser address bar. In my database.cfg I have 


if ($_SERVER['DOCUMENT_ROOT']="localhost") {
   $db['default'] = array(
       'dsn' => '',
       'hostname' => 'localhost',
       'username' => 'root',
       'password' => 'xxxx',  
       'database' => 'substantiator',
       'dbdriver' => 'mysqli',
       'dbprefix' => '',
       'pconnect' => FALSE,
       'db_debug' => (ENVIRONMENT !== 'production'),
       'cache_on' => FALSE,
       'cachedir' => '',
       'char_set' => 'utf8',
       'dbcollat' => 'utf8_general_ci',
       'swap_pre' => '',
       'encrypt' => FALSE,
       'compress' => FALSE,
       'stricton' => FALSE,
       'failover' => array(),
       'save_queries' => TRUE
   );
}
else {

   $db['default'] = array(
       'dsn' => '',
       'hostname' => 'localhost',
       'username' => 'root',
       'password' => 'xxxx',
       'database' => 'substantiator',
       'dbdriver' => 'mysqli',
       'dbprefix' => '',
       'pconnect' => FALSE,
       'db_debug' => (ENVIRONMENT !== 'production'),
       'cache_on' => FALSE,
       'cachedir' => '',
       'char_set' => 'utf8',
       'dbcollat' => 'utf8_general_ci',
       'swap_pre' => '',
       'encrypt' => FALSE,
       'compress' => FALSE,
       'stricton' => FALSE,
       'failover' => array(),
       'save_queries' => TRUE
   );

I also have this in my config.cfg
if ($args[0]="localhost") {
   $config['base_url'] = 'http://localhost//';
} else {
   $config['base_url']='http://54.152.xxx.9/sub_crud/';
}

For some reason, the localhost database seems to always load. It also seems that DOCUMENT_ROOT is unreliable and seems to be set to localhost even though I am using the 54.152.xxx.9/sub_crud in the browser. Is there a better way to do this? The passwords for the databases on the two servers are different. 

proof that an old dog can learn new tricks

@richb201,

You could use the application environment feature of CI...

(setting environment variable) https://codeigniter.com/user_guide/gener...vironments

(setting config variables for specific environments) https://codeigniter.com/user_guide/libra...vironments

I use it for development and production environments which are on different servers.

That is a pretty cool thing. I realized that I should have used == instead of =, so I will try that first.

addendum:

I am going to try ENVIRONMENT since argc fails. One question, how do I set the ENVIRONMENT? I created a config/testing directory. In it I have a localhost centric config.php and database.php as the docs say to do. I then modified the index.php like this:

  define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');
  define ('ENVIRONMENT','testing');

and then I modified a few lines lower to:

switch (ENVIRONMENT)
{
  case 'development':
   case 'testing':
     error_reporting(-1);
      // ini_set("error_reporting", E_ALL & ~E_DEPRECATED); //rnb
     ini_set('display_errors', 1);
  break;

// case 'testing':
  case 'production':

I thought that this would use development, but also use the config/testing config files. But it still uses the regular old config files, instead.

proof that an old dog can learn new tricks

Got it working. I used this code in the index.php

$_SERVER['CI_ENV']='testing';
//define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');
define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');

proof that an old dog can learn new tricks