A First open up confing/config.php for codeIgniter base folder and set as follows:
$system_path = 'core';
$application_folder = 'app';
and finally change both folders name as above.
B First open up index.php from codeIgniter base directory and set as follows:
$system_path = 'core';
$application_folder = 'app';
and finally change both folders name as above.
C First open up confing/constants.php for codeIgniter base folder and set as follows:
$system_path = 'core';
$application_folder = 'app';
and finally change both folders name as above.
D None