PHP error handling mechanism, php processing mechanism_PHP tutorial

PHP error handling mechanism, php processing mechanism

In the daily project development process, there will always be some unexpected exception errors that we don’t expect. If we don’t deal with them, If the processing is perfect, the program will look very unprofessional and may become effective information for others to attack the system; some error exceptions will terminate the execution of the script. If there is no error message at this time, then we can only start from the beginning. Looking at the code, we need to know how terrifying it is for us to have hundreds or thousands of lines of code in the project. So how can we quickly and accurately locate exceptions and errors during the project development process, and make corresponding adjustments? Processing, this article is based on my own understanding of error and exception handling, and I will share it with everyone to learn from each other and serve as a memo.

System error handler:

Under normal circumstances in PHP, errors will be output normally, but in some frameworks, it may affect the error output. It may be that the framework itself has its own processing mechanism, or it may be processed in the code, usually these are Function settings:

1.error_reporting(); Set the error reporting level of PHP and return the current level

error_reporting(report_level)

If the parameter level is not specified, the current error level will be returned. The following are possible values ​​for level:

It is worth noting here that when $level is 0, error output is turned off, that is, no errors will be output.

2.set_error_handler()

Definition and usage

The set_error_handler() function sets a user-defined error handling function.

This function is used to create the user's own error handling method during runtime.

This function returns the old error handler, or null on failure.

Grammar

set_error_handler(error_function,error_types)

Tip: If this function is used, the standard PHP error handling functions are completely bypassed, and the user-defined error handler must terminate (die()) the script if necessary,

Note: If an error occurs before the script is executed, the custom error handler will not be used because the custom program has not been registered at that time.

The test code is as follows:

/**
 *
 * @param type $error_level 错误级别
 * @param type $error_message    错误信息
 * @param type $error_file 可选 错误文件
 * @param type $error_line 可选 错误行
 * @param type $error_context 可选。规定一个数组，包含了当错误发生时在用的每个变量以及它们的值。
 */
function my_error($error_level, $error_message, $error_file, $error_line, $error_context) {
  echo date('Y-m-d H:i:s') . $error_level . $error_message . $error_file . $error_line;
  var_dump($error_context);
}
set_error_handler('my_error', E_ALL);
print_r($a);
 

//From the above case, we can know that when registering the my_error method, the system will automatically overwrite the original error handling error_fuction() method
The result of running the above program:

Custom error trigger

Definition and usage

The trigger_error() function creates a user-defined error message.

trigger_error() is used to trigger an error message under user-specified conditions. It is used with the built-in error handler or with user-defined functions created with the set_error_handler() function.

If an illegal error type is specified, this function returns false, otherwise it returns true.

Grammar

trigger_error(error_message,error_types)

/**
 *
 * @param type $level
 * @param type $msg
 */
function my_error($level, $msg) {
  switch ($level) {
  case E_USER_ERROR:
    echo "ERROR:<br/>";
    break;
  case E_USER_WARNING:
    echo "WARNING:<br/>";
    break;
  case E_USER_NOTICE:
    echo "NOTICE:<br/>";
    break;
  default:
    break;
  }
  echo "错误编号：" . $level . " <br/>";
  echo "错误信息：" . $msg;
}
//注册错误处理器
set_error_handler('my_error');
if (89 > 8) {
  //调用错误触发器
  trigger_error('这是错误啊', E_USER_WARNING);
}

运行结果如下：

WARNING:
错误编号：512
错误信息：这是错误啊

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