PHP output error message and set error level

Method one modifies php.ini

, display error message  
display_errors = on  
; display PHP start error message  
display_startup_errors = on  
; logging error message  
log_errors = On  

Method two need to debug PHP file head join

Ini_set (' display_errors ', 1);            Error message  
ini_set (' display_startup_errors ', 1);    PHP Startup error message  
error_reporting ( -1);                    Print out all error messages  
ini_set (' Error_log ', DirName (__file__). '/error_log.txt '); Output error messages to a text file  

http://php.net/manual/zh/function.ini-set.php
Sets the value of the specified configuration option. This option keeps the new value at the time the script is run and resumes at the end of the script.

http://php.net/manual/zh/function.error-reporting.php
The rror_reporting () function can set the error_reporting instruction at run time. PHP has many error levels that you can use to set the level at which the script runs. If you do not set an optional parameter level, error_reporting () returns only the current error reporting levels.

Error level constant http://php.net/manual/zh/errorfunc.constants.php