PHP master advanced try catch

PHP 5 adds an exception handling module similar to other languages. Exceptions generated in PHP code can be thrown by the throw statement and captured by the catch statement. (Note: You must throw it first to get it)
Code that requires exception handling must be placed in the try code block to catch possible exceptions.
Each try must have at least one corresponding catch.
Use multiple catches to catch exceptions generated by different classes.
When the try code block no longer throws an exception or no catch can be found to match the thrown exception, the PHP code will continue execution after jumping to the last catch.
Of course, PHP allows exceptions to be thrown again within the catch code block.
When an exception is thrown, the subsequent code (Translator's Note: refers to the code block when the exception is thrown) will not continue to execute, and PHP will try to find the first matching catch.

If an exception is not caught and there is no need to use set_exception_handler() for corresponding processing, then PHP will generate a serious error and output Uncaught Exception... (uncaught exception) prompt information.

Let’s first take a look at the basic properties and methods of PHP’s built-in exception class. (Excluding specific implementation)

<?php
/**
* Exception.php
* 
* PHP5内置的异常类的属性与方法
* 以下这段代码只为说明内置异常处理类的结构，它并不是一段有实际意义的可用代码。
*/

class Exception{
	protected $message = &#39;Unknown exception&#39;; // 异常信息
	protected $code = 0; // 用户自定义异常代码
	protected $file; // 发生异常的文件名
	protected $line; // 发生异常的代码行号

	function __construct($message = null, $code = 0);
	final function getMessage(); // 返回异常信息
	final function getCode(); // 返回异常代码（代号）
	final function getFile(); // 返回发生异常的文件名
	final function getLine(); // 返回发生异常的代码行号
	final function getTrace(); // backtrace() 数组
	final function getTraceAsString(); // 已格成化成字符串的 getTrace() 信息

	//可重载的方法
	function __toString(); // 可输出的字符串
}
?>

The example is as follows:

Include file error throws exception

<?php
// 错误的演示
try {
require (&#39;test_try_catch.php&#39;);
} catch (Exception $e) {
echo $e->getMessage();
}
// 正确的抛出异常
try {
if (file_exists(&#39;test_try_catch.php&#39;)) {
require (&#39;test_try_catch.php&#39;);
} else {
throw new Exception(&#39;file is not exists&#39;);
}
} catch (Exception $e) {
echo $e->getMessage();
}

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