How to output PHP errors

PHP is a server-side scripting language used to build web applications. When an error occurs in the PHP code, the error content will be output to help developers quickly locate and fix the problem. This article will introduce how to output PHP errors.

1. Turn on PHP error prompts

In PHP, developers can turn on error prompts by modifying the php.ini file. In this file, you can set the error_reporting and display_errors instructions to the following values ​​to turn on the error prompt:

error_reporting = E_ALL
display_errors = On

The error_reporting instruction is used to set the error level, E_ALL Indicates that all levels of errors are enabled.

The display_errors directive is used to set whether to display error messages in web applications. After setting it to On, you can see error messages in the browser, making it easier for developers to find and solve problems in time.

2. Using the error_reporting function

In addition to modifying the php.ini file, developers can also use the error_reporting function in the code to set the error level. The syntax of this function is as follows:

error_reporting(level);

The level parameter is used to set the error level and can be one of the following constants:

E_ALL: all errors Level
E_ERROR: Fatal error
E_WARNING: Warning
E_NOTICE: Notification
E_STRICT: Standardized warning

For example, the following code sets the error level to E_ALL:

error_reporting(E_ALL);

3. Using the ini_set function

Developers can also use the ini_set function to turn on and off error prompts in the code. The syntax of this function is as follows:

ini_set(setting,value);

The setting parameter is used to set the instruction name, and the value parameter is used to set the value of the instruction. For example, the following code turns on the error prompt:

ini_set('display_errors', 1);

4. Output error message

When the PHP code runs and an error occurs When doing so, error information needs to be output to help developers locate the problem. PHP provides two functions to output error information: error_log and trigger_error.

The error_log function is used to write error information to the error log file. Its syntax is as follows:

error_log(message, message_type, destination, extra_headers);

Among them, the message parameter is the error message; the message_type parameter is the error level, which can be one of the following:

0: System default error level
1: Send mail header
2: Print to Web server log
3: Send to the specified email address
4: Send to the specified email address and specified file
5: Send to the specified file

The destination parameter is the destination address of the error message, and the extra_headers parameter is the additional email header. head.

For example, the following code writes an error message to the error log:

error_log('An unknown error occurred.', 0);

trigger_error function is used to trigger errors, The syntax is as follows:

trigger_error(error_msg, error_type);

The error_msg parameter is the error message and the error_type parameter is the error level. For example, the following code triggers a fatal error:

trigger_error('Fatal error occurred.', E_USER_ERROR);

When an error is triggered, this function displays the error message and stops code execution.

In short, outputting PHP errors is very important and can help developers quickly find and solve problems. By using the above method, developers can freely choose to turn on or off PHP error prompts and send error information to specified targets, thereby improving the robustness and maintainability of the code.

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