(a) CodeIgniter source code Analysis of the index.php

<?PHP/**---------------------------------------------------------------* Application Environment *------------------ ---------------------------------------------* * *//Configure the environment in which the project runs, which affects the display of error reports and the reading of the configuration files. */ Define(' Environment ', ' development ');/**---------------------------------------------------------------* ERROR REPORTING *-------------------------- ------------------------------------- * */if(defined(' Environment ')){ Switch(Environment) { Case' Development ':error_reporting(E_all);  Break;  Case' Testing ': Case' Production ':error_reporting(0);  Break; default:Exit(' The application environment is not set correctly. '); }}/**---------------------------------------------------------------* SYSTEM FOLDER NAME *------------------------ ---------------------------------------* * * Set the system directory*/ $system _path= ' System ';/**---------------------------------------------------------------* application FOLDER NAME *------------------- --------------------------------------------* * * Set app directory*/ $application _folder= ' Application ';/**--------------------------------------------------------------------* DEFAULT CONTROLLER *------------------ -------------------------------------------------- * * */  //The $routing set in the following place will have a redirection effect on the route. See: core/codeiginter.php//$routing [' directory '] = '; $routing [' controller '] = '; $routing [' function '] = ';/**-------------------------------------------------------------------* CUSTOM CONFIG VALUES *------------------ ------------------------------------------------* Here is a place to define configuration information. In fact, in index.php many places can be set up some configuration, like just above the $routing, * and here Set the configuration information to take precedence over the configuration information set in the config/directory. */ //$assign _to_config[' name_of_config_item '] = ' value of config item ';//-------------------------------------------  -------------------------//END of USER configurable SETTINGS. Don't EDIT BELOW this line//--------------------------------------------------------------------/**---------------------------------------------------------------* Resolve The system path for increased Reliabili Ty *---------------------------------------------------------------*/ //Please refer to this: http://blog.163.com/wu_guoqing/blog/static/196537018201272512616394/ if(defined(' STDIN ')) {  chdir(dirname(__file__)); }  //calculates the $system_path, the path where the core file resides. The $path in Realpath ($path) must be a path that exists.  if(Realpath($system _path) !==FALSE) {  $system _path=Realpath($system _path).‘ /‘; } //make sure to/end $system _path=RTrim($system _path, ‘/‘).‘ /‘; //determine if the directory is correct if( !Is_dir($system _path)) {  Exit("Your system folder path does not appear to be set correctly. Please open the following file and correct this: ".PathInfo(__file__,pathinfo_basename)); }/**-------------------------------------------------------------------* After configuring some file directory information above, define some constants according to these directories. * ------------------------------------------------------------------- */ //The file name of this portal file is currently index.php Define(' Self ',PathInfo(__file__,pathinfo_basename)); //file name extension Define(' EXT ', '. php '); //Unified with/For directory separators (default is/) under Windows Yes/or \,linux Define(' BasePath ',Str_replace("\\", "/",$system _path)); //the directory where the front-end controller resides. In CI is this entry file.  Define(' Fcpath ',Str_replace(Self, ",__file__)); //Obtain the directory name of the core file, as follows://trim (Bashpath, '/'): first to trim the Bashpath, remove the end of the '/'//successively through STRRCHR (XXX, '/'): The above-mentioned string, intercept the last one ' /' begins at the end of a substring. Finally trim (XXX, '/'), remove both ends of the '/', the essence here is to remove the left side of the '/'.  Define(' Sysdir ',Trim(STRRCHR(Trim(BasePath, '/'), '/'), '/')); //define the application file directory//First look at whether the directory you configured is relative to the current file, and if so, you can define it successfully.  if(Is_dir($application _folder)) {  Define(' APPPATH ',$application _folder.‘ /‘); } Else {  //if not, then determine whether the application directory exists relative to the core file directory. If not, then pull it down.   if( !Is_dir(BasePath.$application _folder.‘ /‘))  {   Exit("Your Application Folder path does not appear to be set correctly. Please open the following file and correct this: ".Self ); }  Define(' APPPATH ', basepath.$application _folder.‘ /‘); }/**--------------------------------------------------------------------* LOAD the BOOTSTRAP FILE *--------------- ----------------------------------------------------- * */ //In essence, this front-end controller and portal file is just the environment and some constants that define the current project's operation, and the real macro-control is the following codeigniter.php. require_onceBasePath. ' Core/codeigniter.php ';/** Summarize what this file does: * First, set up the current project's operating environment, which is mainly error reporting settings, this is placed in the entire project to run the first place. * Second, the configuration of some directory information, these are certain developers can customize things. Then, depending on the configuration directory information, CI will define something that will be useful later as a constant *, why do you do this? Because in the future in many different places, such as CI in the various components will use the path-related information, where the unified calculation and definition, in the rear * to reference and modify. * Third, the introduction of codeigniter.php to work. * * Move to the core file directory (click:) core/codeigniter.php ...*/

Original address: http://blog.163.com/wu_guoqing/blog/static/196537018201281672320862/

(a) CodeIgniter source code Analysis of the index.php