Analyze PHP5 exception handling with examples_PHP tutorial

＜?php
/**
* ■Exception handling in PHP5
*
* PHP 5 adds an exception handling module similar to other languages. Exceptions generated in PHP code can be thrown
* statement throws and is caught by a catch statement. Code that requires exception handling must be placed within the try code block, ending with
* Catch possible exceptions. Every try must have at least one corresponding catch. Use multiple catches
* Can catch exceptions generated by different classes. When the try code block no longer throws an exception or cannot find a matching catch
* When an exception is thrown, the PHP code will continue executing after jumping to the last catch. Of course, PHP
* Allow exceptions to be thrown again within catch blocks.
* When an exception is thrown, the subsequent code will not continue
* is executed, and PHP will try to find the first matching catch. If an exception is not caught and
* If there is no need to use set_exception_handler() for corresponding processing, then PHP will generate a
* A serious error, and the prompt message Uncaught Exception... (uncaught exception) is output.
*/
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＜?php
/**
* Exception.php
*
* ■㈡The properties and methods of the built-in exception class in PHP5
* The following code is only to illustrate the structure of the built-in exception handling class. It is not a usable code with practical significance.
*/

class Exception{
protected $message = 'Unknown exception'; // Exception message
protected $code = 0; // User-defined exception code
protected $file; // The file name where the exception occurred
protected $line; // Code line number where the exception occurred

function __construct($message = null, $code = 0);
final function getMessage(); // Return exception message
final function getCode(); // Return exception code (code name)
final function getFile(); // Return the file name where the exception occurred
final function getLine(); // Returns the code line number where the exception occurred
final function getTrace(); // backtrace() array
final function getTraceAsString(); // The getTrace() information that has been formatted into a string

Overloadable methods
function __toString(); // Outputable string
}

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＜?php
/**
* syntax .php
*/

//■㈢Grammar structure and analysis

//PHP has two formats for throwing exceptions, as follows

//【1】try...catch...
try {
//Perform abnormal operations, such as database errors and file errors
}catch (Exception $e){
//Print error message
}

//【2】throw
$message='I must be run in the try{} block. If an exception occurs, I ($message) will be returned (passed) to the instance of the exception object in catch(), such as $e above';
$code=123; //Error code number, you can use $e->getCode(); in the catch block to return my value 123, so that I can customize the error code number

throw new Exception($message,$code);

//Note when learning JAVA, PHP exception handling does not have throws

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＜?php
/**
* Example.php
*/
//■㈣Two examples to master PHP exception handling


//Example [1] use try...catch
/* PDO connects to the mysql database. If you have not seen PDO, first look at the constructor of PDO, or skip Example 1 and look at Example 2 */
$dsn = 'mysql:host=localhost;dbname=testdb';
$user = 'dbuser';
$password = 'dbpass';

try {
$dbh = new PDO($dsn, $user, $password); //Creating a database connection object is prone to exceptions
echo 'If there is an exception above, I will not be displayed';
} catch (PDOException $e) {
echo 'Connection failed: ' . $e-＞__toString();
}
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＜?php
//Example[2] try..cathc and throw are used together
try {
$error = 'I threw an exception message and jumped out of the try block';
if(is_dir('./tests')){
echo 'do sth.';
}else{
throw new Exception($error,12345);
}
echo 'If there is an exception above, it won't be my turn! ~＜br /＞',"n";
} catch (Exception $e) {
echo 'Catch exception: ', $e-＞getMessage(),$e-＞getCode(), "n＜br /＞"; //Display $error and 123456
}
echo 'Continue execution';
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＜?php
//PHP's processing is much easier to learn than JAVA, because JAVA has too many exception classes, throws, etc.
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http://www.bkjia.com/PHPjc/371514.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/371514.htmlTechArticle＜?php /** * ■㈠Exception handling in PHP5* * PHP 5 adds exceptions similar to other languages processing module. Exceptions generated in PHP code can be thrown by the throw * statement and caught by the catch statement...