Codeigniter error: Call to undefined function mysql_pconnect()

Deprecated features in PHP 5.5.x:

The original MySQL extension is now deprecated, and will generate E_DEPRECATED errors when connecting to a database. Instead, use the MySQLi or PDO_MySQL extensions.

You're using the deprecated 'mysql' dbdriver. Locate the config/database.php file and change dbdriver to use 'mysqli' :

$db['default']['dbdriver'] = 'mysqli'; 

Thanks to Anant

I come to a conclusion:

I completely changed my old database.php file in config folder with the new one:

From:

$db['default']['hostname'] = 'localhost';$db['default']['username'] = '';$db['default']['password'] = '';$db['default']['database'] = '';$db['default']['dbdriver'] = '';$db['default']['dbprefix'] = '';$db['default']['pconnect'] = TRUE;$db['default']['db_debug'] = TRUE;$db['default']['cache_on'] = FALSE;$db['default']['cachedir'] = '';$db['default']['char_set'] = 'utf8';$db['default']['dbcollat'] = 'utf8_general_ci';$db['default']['swap_pre'] = '';$db['default']['autoinit'] = TRUE;$db['default']['stricton'] = FALSE;

To:

$db['default'] = array(    'dsn'   => '',    'hostname' => '',    'username' => '',    'password' => '',    'database' => '',    '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);

And the error is gone!

go to application/config/database.php
and just change mysql to mysqli

like this was before:

 $db['default']['dbdriver'] = 'mysql';

this was after solution:

$db['default']['dbdriver'] = 'mysqli';

i just change mysql to mysqli. that's it

my error was

Fatal error: Uncaught Error: Call to undefined function mysql_pconnect() in E:\manish_data\software\xampp\htdocs\ci2\system\database\drivers\mysql\mysql_driver.php:92 Stack trace: #0 E:\manish_data\software\xampp\htdocs\ci2\system\database\DB_driver.php(116): CI_DB_mysql_driver->db_pconnect() #1 E:\manish_data\software\xampp\htdocs\ci2\system\database\DB.php(149): CI_DB_driver->initialize() #2 E:\manish_data\software\xampp\htdocs\ci2\system\core\Loader.php(347): DB(Array, NULL) #3 E:\manish_data\software\xampp\htdocs\ci2\application\models\usermodel.php(20): CI_Loader->database() #4 E:\manish_data\software\xampp\htdocs\ci2\application\controllers\users.php(15): UserModel->getUsers() #5 E:\manish_data\software\xampp\htdocs\ci2\system\core\CodeIgniter.php(360): Users->index() #6 E:\manish_data\software\xampp\htdocs\ci2\index.php(202): require_once('E:\manish_data\...') #7 {main} thrown in E:\manish_data\software\xampp\htdocs\ci2\system\database\drivers\mysql\mysql_driver.php on line 92