How to customize error prompts in php

In PHP, you can customize error handling through the "set_error_handler()" function. The function of this function is to specify another function as the error handling function, with syntax such as "set_error_handler(callable $error_handler...)".

The operating environment of this article: Windows 7 system, PHP version 7.1, DELL G3 computer

How to customize error prompts in php?

PHP set_error_handler(): Custom error handling function

PHP provides a set_error_handler() function, which can be used to specify another function as error handling Function, its syntax is as follows:

set_error_handler(callable $error_handler [, int $error_types = E_ALL | E_STRICT ])

Parameter description

1) $error_handler is a user-defined function name. In addition to the function name, you can also pass in NULL reset handler to In the default state, you can also pass in an array of reference objects and object method names.

The format of the user-defined function is as follows:

error_handler(int $errno , string $errstr [, string $errfile [, int $errline [, array $errcontext ]]])

Among them:

The first parameter $errno represents the error level and is an integer type;

The second parameter $errstr represents the error information, which is a string type;

The third parameter $errfile is an optional parameter, which represents the file name where the error occurred, and is a string type;

The fourth parameter $errline is also an optional parameter, indicating the line number where the error occurred, and is an integer type;

The fifth parameter $errcontext is also an optional parameter (in PHP7.2.0 Later deprecated), represents an array of active symbol tables when the error occurred. That is to say, $errcontext will contain an array of all variables in the scope where the error was triggered. The user's error handler should not modify the error context.

Note: If the set_error_handler() function returns FALSE, the standard error handler will continue to be called.

2) The $error_types parameter is just like the error_reporting in the configuration file php.ini that can control the display of errors. This parameter can be used to block the triggering of $error_handler. Without this mask, $error_handler will be called on every error regardless of how $error_reporting is set.

If an error handler has been defined before, the program name is returned; if it is a built-in error handler, NULL is returned. If an invalid callback function is specified, NULL will also be returned. If the previous error handler was a class method, this function returns an indexed array with the class and method names.

[Example] Customize an error handling function and use it to handle errors in the program.

"; echo "error msg：".$errstr."
"; echo "error file：".$errfile."
"; echo "error line：".$errline."
"; die('something error'); } set_error_handler("error_handler"); strpos(); ?>

The running results are as follows:

error number：2 error msg：strpos() expects at least 2 parameters, 0 given error file：D:\WWW\index.php error line：10 something error

Note: Use this method for error handling. If the execution of the program is not terminated in the error handling function, the program will continue to execute the next line where the error occurred. , so the die() function needs to be used to terminate the program.

It should also be noted that this error handling method cannot take over all levels of program errors. Errors in the E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR, E_COMPILE_WARNING and E_STRICT parts will be displayed in their original form. come out.

set_error_handler() Advanced

PHP’s exception handling mechanism is not perfect and cannot automatically throw exceptions. Users can also use set_error_handler() to handle exceptions as errors, so Users can use custom error handling functions to automatically catch exceptions.

[Example] Use a custom error handling function to automatically catch exceptions.

"; echo "error msg：".$errstr."
"; echo "error file：".$errfile."
"; echo "error line：".$errline."
"; die('something error'); } set_error_handler("error_handler"); /* 触发异常 */ try { $a = 5/0; echo $a; } catch(Exception $e) { echo $e->getMessage(); } ?>

The running results are as follows:

error number：2 error msg：Division by zero error file：D:\WWW\index.php error line：12 something error

When the program executes to the $a = 5/0; statement in line 12, the program will automatically capture this exception and use the user-defined function for processing.

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