PHP error handling instance methods

1. Php default error handling method

In PHP, the default error handling is very simple. A message is sent to the browser with the file name, line number, and a message describing the error. Error handling is an important part when creating scripts and web applications. If your code lacks error detection coding, the program will look unprofessional and open the door to security risks.

2. Improved processing method:

1. Simple "die()" statement

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

3. Custom errors and error triggers

3. PHP error level:

1 E_ERROR Fatal runtime error. The error cannot be recovered. Execution of the script was suspended

2 E_WARNING Non-fatal run-time error. The execution of the script will not stop

4 E_PARSE Compile time parsing error. Parsing errors should only be run-time notifications generated by the parser.

16 E_CORE_ERROR Fatal error when starting PHP. This is like a non-fatal error in PHP core E_ERROR

32 E_CORE_WARNING when PHP starts. This is like an E_WARNING warning

64 E_COMPILE_ERROR fatal compile-time error in the PHP core. This is like an E_ERROR

128 E_COMPILE_WARNING non-fatal compile-time error generated by the Zend Scripting Engine, and an E_WARNING warning

256 E_USER_ERROR fatal user-generated error generated by the Zend Scripting Engine.

512 E_USER_WARNING Non-fatal user-generated warning.

1024 E_USER_NOTICE User-generated notification.

2048 E_STRICT Enables PHP's suggestions for code modifications to ensure the best interoperability and forward compatibility of the code.

4096 E_RECOVERABLE_ERROR Catches fatal errors.

8191 E_ALL All errors and warnings.

4. php error reporting:

php does not enable error reporting by default. There are two ways to prompt errors:

1. Configure the php.ini file:

Change display_errors =Off to display_errors = On

php displays all errors by default, but we do not need to display some harmless prompts. In addition, we must also configure the error level: error_reporting = E_ALL Change to: error_reporting = e_all & ~ e_notice

## ：: Error reflection is generally used for development mode, but errors can reveal a lot of sensitive information, providing convenience for the attacker's next attack. In a formal environment, it is recommended to turn off this option and set log_error=on. If an error occurs at this time, it will prompt: Server error, but no error prompt will appear and the error information will be recorded in the log.

2. Add

<?php
  error_reporting(0); // 关闭错误报告
  error_reporting(E_ERROR | E_WARNING | E_PARSE); // 报告 runtime 错误
  error_reporting(E_ALL); // 报告所有错误
  error_reporting(E_ALL & ~E_NOTICE); // 报告 E_NOTICE 之外的所有错误
?>

5. Custom error handler and error trigger

Custom error handler:

user_error_function(error_level,error_message,error_file,error_line,error_context)(用户自己定义,用在set_error_handler中调用)

error_level: required (error level)                                                                                                                                                                        ​Information)

set_error_handler():

If this function is used, the standard PHP error handling functions will be completely bypassed (error_reporting () will fail), and if necessary, user-defined errors The handler must terminate (die() ) the script.

set_error_handler() requires only one parameter (custom error handler), and a second parameter can be added to specify the error level.

trigger_error()触发错误

在脚本中用户输入数据的位置，当用户的输入无效时触发错误的很有用的。可以在脚本中任何位置触发错误，通过添加的第二个参数，您能够规定所触发的错误级别。可能的错误类型：E_USER_ERROR, E_USER_WARNING, E_USER_NOTIC.

例子：

//自定义错误处理器
function myErrorHandler($errno, $errstr, $errfile,$errline){
    if(!(error_reporting() &$errno)){return;}
    switch ($errno){
    case E_USER_ERROR:
        echo "<b>MyERROR</b> [$errno] $errstr<br/>";
        echo "错误行：$errline 在文件：$errfile之中<br/>";
        echo " PHP版本： " .PHP_VERSION ." (" .PHP_OS .")<br/>";
        break;
    case E_USER_WARNING:
        echo "<b>MyWARNING</b> [$errno] $errstr<br/>";
        break;
    case E_USER_NOTICE:
        echo "<b>MyNOTICE</b> [$errno] $errstr<br />";
        break;
    default:
        echo "Unknown error type:[$errno] $errstr<br />";
        break;
    }
    return true;
}
//测试函数
functiontrigger_test($age){   
if($age <= 0|| $age > 999)    trigger_error("年龄不合法：$age岁",E_USER_ERROR);
if($age < 18)         trigger_error("未成年：$age岁",E_USER_WARNING);
if($age > 40&& $age < 100)     trigger_error("年龄稍大：$age岁",E_USER_NOTICE);
}
//如果只是简单统一地处理错误：
$errorHandler = set_error_handler("myErrorHandler");
trigger_test(1000);//会抛出一个error级的错误
//如果要分别处理不同错误级别则需要构造不同级别的错误处理器
function myError($errno, $errstr,$errfile, $errline){
    //具体处理方法
}
function myWarning($errno, $errstr, $errfile, $errline){
    //具体处理方法
}
function myNtice($errno, $errstr, $errfile, $errline){
    //具体处理方法
}
set_error_handler(&#39;myError&#39;,E_USER_ERROR);
set_exception_handler(&#39;myWarning&#39;,E_USER_WARNING);
set_exception_handler(&#39;myNtice&#39;,E_USER_NOTICE);
trigger_error(&#39;故意抛出个错误，还是很严重的哪一种！&#39;,E_USER_ERROR);

6. 屏蔽PHP错误提示

方法一：

在有可能出错的函数前加@,然后or die("") 

如： @mysql_connect(...) or die("Database Connect Error")

注：@其实它是错误抑制符，即即使出现错误，也无视出现的错误信息，继续执行下边的代码；好处是不会输出错误信息。

Or die当在脚本中调用die()和exit()时，将会终止整个脚本。它们都可用于阻止脚本继续执行，而使得某些重要的操作（如建立一条数据库连接）不会发生。你还可以给die()和exit()传递一个将在浏览器中打印出来的字符串。

方法二：

编辑php.ini ，将"display_errors =off" , 同时将log_error=on, error_log = /var/log/php-error.log

方法三：

在php脚本前加error_reporting(0)，屏蔽所有错误提示。
其中，error_reporting 配置错误信息回报的等级。
语法：int error_reporting(int [level]);
返回值：整数
函数种类：PHP 系统功能

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