利用 php 本身寫 error log 及 error/warning/notice message

• error_reporting
  設定php回發生錯誤的等級
  

  error_reporting(0);  // Turn off all error reporting
  ini_set('error_reporting', E_ALL);  // Same as error_reporting(E_ALL);

• error_log
  bool error_log ( string $message [, int $message_type = 0 [, string $destination [, string $extra_headers ]]] )
  Sends an error message to the web server's error log or to a file.
  需寫入file，因此需指定file path
  用法
  

  //log to file
  ini_set('error_log', dirname(__FILE__) . '/error_log.txt');  
  
  // Send notification through the server log if we can not
  // connect to the database.
  if (!Ora_Logon($username, $password)) {
      error_log("Oracle database not available!", 0);
  }
  
  // Notify administrator by email if we run out of FOO
  if (!($foo = allocate_new_foo())) {
      error_log("Big trouble, we're all out of FOOs!", 1,
                 "operator@example.com");
  }
  
  // another way to call error_log():
  error_log("You messed up!", 3, "/var/tmp/my-errors.log");
  

• error/warning/notice message
  定義log level多配合log4php，不過也可透過trigger_error
  即可靠php本身達成此效果
  

  trigger_error("Notice Message",E_USER_NOTICE);
  trigger_error("Warning Message",E_USER_WARNING);
  trigger_error("Error Message",E_USER_ERROR);

  如此就不用再掛log4php，就能方便帶訊息
  

也就是說error_report 是設定php觸發回報錯誤的等級
如果想利用此機制寫自定的訊息就可透過trigger_error
而error_log就自己想log什麼就log什麼

error_report設定篇
開啟是否顯示error及log的等級

• 在php.ini中設定
  

  display_errors = On 
  

• 在.php中設定
  每次要到php.ini設定就太累了，這邊有方法可以直接在.php裡，直接設定log，這樣開發起來就方便多了，且不會動到整體環境
  

  ini_set('display_errors', 1);   //turn on display error on screen
  ini_set('log_errors', 1);     //turn on log error
  error_reporting(E_ALL); //log all errors and warnings

常見常數定義
列出常見的幾個，其他看官網Predefined Constants

Constant	Description	Note
E_NOTICE	Run-time notices. Indicate that the script encountered something that could indicate an error, but could also happen in the normal course of running a script.
E_STRICT	Enable to have PHP suggest changes to your code which will ensure the best interoperability and forward compatibility of your code.	Since PHP 5 but not included in E_ALL until PHP 5.4.0
E_ALL	All errors and warnings, as supported, except of level E_STRICT prior to PHP 5.4.0.

References