The most common error mechanism we use in PHP is try catch{}, which can easily catch errors. However, PHP also provides error viewing and error closing for many things. This can be found in php.ini During processing, you can also add error_display(0); at the beginning of the file to not display errors
The code is as follows | Copy code | ||||||||||||||||||||
$f=fopen('test.txt','r'); //Close after use
|
The code is as follows | Copy code |
if(!file_exists('aa.txt')){ die('File does not exist'); } else { //Perform operation } //If die() above is triggered, then the echo connection here will not be executed echo 'ok'; |
The code is as follows | Copy code |
file_exits('aaa.txt') or die('File does not exist'); echo 'ok'; |
B. Custom errors and error triggers
1. Error handler (custom error, generally used for syntax error handling)
Create a custom error function (handler) that must be able to handle at least two parameters (error_level and errormessage), but can accept up to five parameters (error_file, error_line, error_context)
Syntax:
function error_function($error_level,$error_message,$error_file,$error_line,$error_context)
//After creation, you need to rewrite the set_error_handler(); function
set_error_handler('error_function',E_WARNING); //Here error_function corresponds to the custom handler name created above, and the second parameter is the error level using the custom error handler;
Error reporting level (just understand it)
These error reporting levels are different types of errors that error handlers are designed to handle:
Value Constant Description
2 E_WARNING Nonfatal run-time error. Do not pause script execution.
8 E_NOTICE Run-time notification.
Script discovery errors may occur, but may also occur while the script is running normally.
256 E_USER_ERROR Fatal user-generated error. This is similar to E_ERROR set by the programmer using the PHP function trigger_error().
512 E_USER_WARNING Non-fatal user-generated warning. This is similar to the E_WARNING set by the programmer using the PHP function trigger_error().
1024 E_USER_NOTICE User-generated notification. This is similar to E_NOTICE set by the programmer using the PHP function trigger_error().
4096 E_RECOVERABLE_ERROR Trapable fatal error. Like E_ERROR, but can be caught by a user-defined handler. (see set_error_handler())
8191 E_ALL All errors and warnings except level E_STRICT.
(In PHP 6.0, E_STRICT is part of E_ALL)
2. Error trigger (generally used to handle logical errors)
Requirement: For example, if you want to receive an age, if the number is greater than 120, it is considered an error
Traditional method:
if($age>120){
echo 'Wrong age';exit();
}
Use triggers:
if($age>120){
//trigger_error('error message'[,'error level']); The error level here is optional and is used to define the level of the error
//User-defined levels include the following three types: E_USER_WARNING, E_USER_ERROR, E_USER_NOTICE
trigger_error('age error');//This is the default error handling method of the calling system, we can also use a custom processor
}
//Custom processor, same as above
function myerror($error_level,$error_message){
echo 'error text';
}
//At the same time, the system default processing function needs to be changed
set_error_handler('myerror',E_USER_WARNING);//Same as above, the first parameter is the name of the custom function, and the second parameter is the error level [The error levels here are usually the following three: E_USER_WARNING, E_USER_ERROR, E_USER_NOTICE]
//Now you can use the custom error handling function by using trigger_error
Practice questions:
The code is as follows | Copy code | ||||
$info= "Error number: $error_leveln"; } else { echo 'File'.$filename.'Not writable'; }
exit();
} <🎜>
set_error_handler('myerror',E_WARNING); <🎜>
$fp=fopen('aaa.txt','r'); <🎜>
?>
|