How does error handling work in PHP functions? How to customize error handling?

The error handling mechanism of PHP functions allows developers to define how to handle errors and exceptions. By default, error messages are logged and displayed on standard error, but developers can customize error handling using the set_error_handler() function. You can customize error handling by setting a callback function that will be called when an error occurs and log information such as error information, error level, error file, and line number.

Error handling in PHP functions

Introduction

PHP provides a powerful error handling mechanism that allows Developers control how errors and exceptions in functions are handled. This article will introduce how error handling works in PHP functions and how to customize error handling.

Error handling mechanism

The default error handling mechanism in the PHP function is as follows:

1. When an error occurs in the function, it will trigger a mistake.
2. The PHP engine records error information to the log and displays it in the standard error output (stderr).
3. The script will not stop execution unless the error is fatal (such as a syntax error).

Custom error handling

In order to customize error handling, you can use the set_error_handler() function. This function accepts a callback function as a parameter, which will be called when an error occurs in the function.

// 自定義錯誤處理函式
function my_error_handler($error_level, $error_message, $error_file, $error_line)
{
    // 處理錯誤訊息
    echo "錯誤級別：{$error_level}\n";
    echo "錯誤訊息：{$error_message}\n";
    echo "錯誤檔案：{$error_file}\n";
    echo "錯誤行號：{$error_line}\n";
}

// 設定自定義錯誤處理函式
set_error_handler("my_error_handler");

Practical case

The following is an example of a custom error handling function, which records error information to a file:

// 自定義錯誤處理函式
function log_error($error_level, $error_message, $error_file, $error_line)
{
    // 將錯誤訊息記錄到檔案中
    file_put_contents('errors.log', "錯誤級別：{$error_level}\n錯誤訊息：{$error_message}\n錯誤檔案：{$error_file}\n錯誤行號：{$error_line}\n\n", FILE_APPEND);
}

// 設定自定義錯誤處理函式
set_error_handler("log_error");

// 觸發一個錯誤
trigger_error("這是自定義錯誤訊息", E_USER_NOTICE);

When When an error occurs, error information will be logged to the errors.log file.

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