PHP error handling and debugging skills

PHP error handling and debugging skills include: Error types: E_ERROR, E_WARNING, E_NOTICE Error handling functions: register_shutdown_function(), set_error_handler(), error_get_last() Custom error handling functions: used to record or handle errors and prevent program termination Error debugging skills: check logs, use exception handling, enable PHP to display errors, use online debugger

PHP error handling and debugging skills

PHP’s error handling is critical to developing robust and reliable applications. Here are some tips to help you handle and debug PHP errors effectively:

Error Types

PHP errors are divided into the following types:

• E_ERROR: Serious error, program cannot continue execution.
• E_WARNING: Non-critical error, but may cause unexpected behavior.
• E_NOTICE: Non-fatal error, usually indicating improper use of PHP.

Error handling function

PHP provides the following error handling function:

• ##register_shutdown_function() : Called at the end of script execution to report a fatal error.
• set_error_handler(): Set a custom function to handle errors.
• error_get_last(): Get the latest error information.

Example error handling function

The following is an example error handling function that logs fatal errors to the log file:

function error_handler(int $errno, string $errstr, string $errfile, int $errline)
{
    $message = sprintf("Error (%d): %s in %s on line %d", $errno, $errstr, $errfile, $errline);
    file_put_contents('error_log.txt', $message);
}

Using a custom error handling function

To use a custom error handling function, call

set_error_handler() at the beginning of the script:

set_error_handler('error_handler');

Error Debugging Tips

Here are some tips to help you debug PHP errors:

Check the server logs.
Use exception handling.
Enable PHP to display errors.
Use the online debugger.

Practical Example

Suppose you have a PHP script that tries to read a file that does not exist. This error results in a fatal error.

$file = "/path/to/non-existent-file.txt";
$contents = file_get_contents($file);

To handle this error, you can use a custom error handling function:

function error_handler(int $errno, string $errstr, string $errfile, int $errline)
{
    if ($errno === E_ERROR) {
        // 记录错误
    }
}

set_error_handler('error_handler');

This way, when the script tries to read a file that does not exist, the error will be logged and the program will continue implement.

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