1、Ci的报错级别设置一般在index.php中，可以设置ENVIRONMENT。一般来讲，开发的时候选择development模式，正式发布之后，选择production模式。
代码如下：
/*
*---------------------------------------------------------------
* APPLICATION ENVIRONMENT
*---------------------------------------------------------------
*
* You can load different configurations depending on your
* current environment. Setting the environment also influences
* things like logging and error reporting.
*
* This can be set to anything, but default usage is:
*
* development
* testing
* production
*
* NOTE: If you change these, also change the error_reporting() code below
*
*/
define('ENVIRONMENT', 'development');
/*
*---------------------------------------------------------------
* ERROR REPORTING
*---------------------------------------------------------------
*
* Different environments will require different levels of error reporting.
* By default development will show errors but testing and live will hide them.
*/
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.');
}
}
2、CI的错误日志默认存放在application/logs/log-[time].php中，日志的级别、路径、时间格式等，在application/config/config.php文件中设置，相关代码如下：
/*
|--------------------------------------------------------------------------
| Error Logging Threshold
|--------------------------------------------------------------------------
|
| If you have enabled error logging, you can set an error threshold to
| determine what gets logged. Threshold options are:
| You can enable error logging by setting a threshold over zero. The
| threshold determines what gets logged. Threshold options are:
|
| 0 = Disables logging, Error logging TURNED OFF
| 1 = Error Messages (including PHP errors)
| 2 = Debug Messages
| 3 = Informational Messages
| 4 = All Messages
|
| For a live site you'll usually only enable Errors (1) to be logged otherwise
| your log files will fill up very fast.
|
*/
$config['log_threshold'] = 0;
/*
|--------------------------------------------------------------------------
| Error Logging Directory Path
|--------------------------------------------------------------------------
|
| Leave this BLANK unless you would like to set something other than the default
| application/logs/ folder. Use a full server path with trailing slash.
|
*/
$config['log_path'] = '';
/*
|--------------------------------------------------------------------------
| Date Format for Logs
|--------------------------------------------------------------------------
|
| Each item that is logged has an associated date. You can use PHP date
| codes to set your own date formatting
|
*/
$config['log_date_format'] = 'Y-m-d H:i:s';
3、在自己写代码需要记录日志时，可以调用全局函数log_message('级别','消息')，级别的参数为(调试 debug, 错误 error, 信息info)，内容自己定义即可。
log_message('error', 'error message.');
log_message('debug', 'debug message.');
log_message('info', 'info message.');
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