blocks|key|1562980|text|异常是由代码故意使用抛出、错误...不是很多。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1562981|错误是由于一些通常不能处理的事情而产生的。(IO错误、TCP/IP错误、空引用错误)|1562982|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

<p>Exceptions are thrown intentionally by code using a throw, errors... not so much. </p>

<p>Errors come about as a result of something which isn't handled typically. (IO errors, TCP/IP errors, null reference errors) </p>


blocks|key|1563073|text|异常是thrown+-它们旨在被捕获。错误通常是不可恢复的。比方说，您有一段代码将向数据库中插入一行。这个调用可能会失败(重复ID)+--你会想要一个"Error“，在本例中是一个"Exception”。当您插入这些行时，您可以这样做|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1563074|try+{
++$row->insert();
++$inserted+=+true;
}+catch+(Exception+$e)+{
++echo+"There+was+an+error+inserting+the+row+-+".$e->getMessage();
++$inserted+=+false;
}

echo+"Some+more+stuff";|code-block|syntax|javascript|1563075|程序将继续执行-因为您“捕获”了异常。异常将被视为错误，除非它被捕获。它将允许您在程序失败后继续执行程序。|1563076|entityMap|0|LINK|mutability|MUTABLE|url|http://us3.php.net/throw^0|3|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

<p>Exceptions are <a href="http://us3.php.net/throw" rel="noreferrer">thrown</a> - they are intended to be caught.  Errors are generally unrecoverable.  Lets say for instance - you have a block of code that will insert a row into a database.  It is possible that this call fails (duplicate ID) - you will want to have a "Error" which in this case is an "Exception".  When you are inserting these rows, you can do something like this</p>

<pre><code>try {
  $row-&gt;insert();
  $inserted = true;
} catch (Exception $e) {
  echo "There was an error inserting the row - ".$e-&gt;getMessage();
  $inserted = false;
}

echo "Some more stuff";
</code></pre>

<p>Program execution will continue - because you 'caught' the exception.  An exception will be treated as an error unless it is caught.  It will allow you to continue program execution after it fails as well.</p>


blocks|key|1347635|text|这里要添加的一件事是关于处理异常和错误。对于应用程序开发人员来说，错误和异常都是“不好的东西”，您希望记录它们以了解应用程序存在的问题-以便您的客户在长期内有更好的体验。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1347636|因此，编写一个错误处理程序来做与处理异常相同的事情是有意义的。|1347637|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

<p>One thing to add here is about handling exceptions and errors. For the purpose of the application developer, both errors and exceptions are "bad things" that you want to record to learn about the problems that your application has - so that your customers have a better experience in the long run. </p>

<p>So it makes sense to write an error handler that does the same thing as what you do for exceptions.</p>


blocks|key|1347725|text|我通常set_error_handler到一个接受错误并抛出异常的函数，这样无论发生什么，我都会有异常需要处理。没有更多的@file_get_contents，只是漂亮和整洁的try/catch。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1347726|在调试情况下，我还有一个异常处理程序，它输出一个类似asp.net的页面。我在路上发布了这篇文章，但如果需要的话，我会在稍后发布示例源代码。|1347727|编辑：|1347728|此外，正如我所承诺的，我已经将我的一些代码剪切并粘贴在一起，以制作一个样本。|1347729|<?php

define(+'DEBUG',+true+);

class+ErrorOrWarningException+extends+Exception
{
++++protected+$_Context+=+null;
++++public+function+getContext()
++++{
++++++++return+$this->_Context;
++++}
++++public+function+setContext(+$value+)
++++{
++++++++$this->_Context+=+$value;
++++}
++++
++++public+function+__construct(+$code,+$message,+$file,+$line,+$context+)
++++{
++++++++parent::__construct(+$message,+$code+);

++++++++$this->file+=+$file;
++++++++$this->line+=+$line;
++++++++$this->setContext(+$context+);
++++}
}

/**
+*+Inspire+to+write+perfect+code.+everything+is+an+exception,+even+minor+warnings.
+**/
function+error_to_exception(+$code,+$message,+$file,+$line,+$context+)
{
++++throw+new+ErrorOrWarningException(+$code,+$message,+$file,+$line,+$context+);
}
set_error_handler(+'error_to_exception'+);

function+global_exception_handler(+$ex+)
{
++++ob_start();
++++dump_exception(+$ex+);
++++$dump+=+ob_get_clean();
++++//+send+email+of+dump+to+administrator?...

++++//+if+we+are+in+debug+mode+we+are+allowed+to+dump+exceptions+to+the+browser.
++++if+(+defined(+'DEBUG'+)+&&+DEBUG+==+true+)
++++{
++++++++echo+$dump;
++++}
++++else+//+if+we+are+in+production+we+give+our+visitor+a+nice+message+without+all+the+details.
++++{
++++++++echo+file_get_contents(+'static/errors/fatalexception.html'+);
++++}
++++exit;
}

function+dump_exception(+Exception+$ex+)
{
++++$file+=+$ex->getFile();
++++$line+=+$ex->getLine();

++++if+(+file_exists(+$file+)+)
++++{
++++++++$lines+=+file(+$file+);
++++}
++++
?><html>
++++<head>
++++++++<title><?=+$ex->getMessage();+?></title>
++++++++<style+type="text/css">
++++++++++++body+{
++++++++++++++++width+:+800px;
++++++++++++++++margin+:+auto;
++++++++++++}
++++++++
++++++++++++ul.code+{
++++++++++++++++border+:+inset+1px;
++++++++++++}
++++++++++++ul.code+li+{
++++++++++++++++white-space:+pre+;
++++++++++++++++list-style-type+:+none;
++++++++++++++++font-family+:+monospace;
++++++++++++}
++++++++++++ul.code+li.line+{
++++++++++++++++color+:+red;
++++++++++++}
++++++++++++
++++++++++++table.trace+{
++++++++++++++++width+:+100%25;
++++++++++++++++border-collapse+:+collapse;
++++++++++++++++border+:+solid+1px+black;
++++++++++++}
++++++++++++table.thead+tr+{
++++++++++++++++background+:+rgb(240,240,240);
++++++++++++}
++++++++++++table.trace+tr.odd+{
++++++++++++++++background+:+white;
++++++++++++}
++++++++++++table.trace+tr.even+{
++++++++++++++++background+:+rgb(250,250,250);
++++++++++++}
++++++++++++table.trace+td+{
++++++++++++++++padding+:+2px+4px+2px+4px;
++++++++++++}
++++++++</style>
++++</head>
++++<body>
++++++++<h1>Uncaught+<?=+get_class(+$ex+);+?></h1>
++++++++<h2><?=+$ex->getMessage();+?></h2>
++++++++<p>
++++++++++++An+uncaught+<?=+get_class(+$ex+);+?>+was+thrown+on+line+<?=+$line;+?>+of+file+<?=+basename(+$file+);+?>+that+prevented+further+execution+of+this+request.
++++++++</p>
++++++++<h2>Where+it+happened:</h2>
++++++++<?+if+(+isset($lines)+)+:+?>
++++++++<code><?=+$file;+?></code>
++++++++<ul+class="code">
++++++++++++<?+for(+$i+=+$line+-+3;+$i+<+$line+%2B+3;+$i+%2B%2B+)+:+?>
++++++++++++++++<?+if+(+$i+>+0+&&+$i+<+count(+$lines+)+)+:+?>
++++++++++++++++++++<?+if+(+$i+==+$line-1+)+:+?>
++++++++++++++++++++++++<li+class="line"><?=+str_replace(+"\n",+"",+$lines[$i]+);+?></li>
++++++++++++++++++++<?+else+:+?>
++++++++++++++++++++++++<li><?=+str_replace(+"\n",+"",+$lines[$i]+);+?></li>
++++++++++++++++++++<?+endif;+?>
++++++++++++++++<?+endif;+?>
++++++++++++<?+endfor;+?>
++++++++</ul>
++++++++<?+endif;+?>

++++++++<?+if+(+is_array(+$ex->getTrace()+)+)+:+?>
++++++++<h2>Stack+trace:</h2>
++++++++++++<table+class="trace">
++++++++++++++++<thead>
++++++++++++++++++++<tr>
++++++++++++++++++++++++<td>File</td>
++++++++++++++++++++++++<td>Line</td>
++++++++++++++++++++++++<td>Class</td>
++++++++++++++++++++++++<td>Function</td>
++++++++++++++++++++++++<td>Arguments</td>
++++++++++++++++++++</tr>
++++++++++++++++</thead>
++++++++++++++++<tbody>
++++++++++++++++<?+foreach+(+$ex->getTrace()+as+$i+=>+$trace+)+:+?>
++++++++++++++++++++<tr+class="<?=+$i+%25+2+==+0+?+'even'+:+'odd';+?>">
++++++++++++++++++++++++<td><?=+isset($trace[+'file'+])+?+basename($trace[+'file'+])+:+'';+?></td>
++++++++++++++++++++++++<td><?=+isset($trace[+'line'+])+?+$trace[+'line'+]+:+'';+?></td>
++++++++++++++++++++++++<td><?=+isset($trace[+'class'+])+?+$trace[+'class'+]+:+'';+?></td>
++++++++++++++++++++++++<td><?=+isset($trace[+'function'+])+?+$trace[+'function'+]+:+'';+?></td>
++++++++++++++++++++++++<td>
++++++++++++++++++++++++++++<?+if(+isset($trace[+'args'+])+)+:+?>
++++++++++++++++++++++++++++++++<?+foreach+(+$trace[+'args'+]+as+$i+=>+$arg+)+:+?>
++++++++++++++++++++++++++++++++++++<span+title="<?=+var_export(+$arg,+true+);+?>"><?=+gettype(+$arg+);+?></span>
++++++++++++++++++++++++++++++++++++<?=+$i+<+count(+$trace['args']+)+-1+?+','+:+'';+?>+
++++++++++++++++++++++++++++++++<?+endforeach;+?>
++++++++++++++++++++++++++++<?+else+:+?>
++++++++++++++++++++++++++++NULL
++++++++++++++++++++++++++++<?+endif;+?>
++++++++++++++++++++++++</td>
++++++++++++++++++++</tr>
++++++++++++++++<?+endforeach;?>
++++++++++++++++</tbody>
++++++++++++</table>
++++++++<?+else+:+?>
++++++++++++<pre><?=+$ex->getTraceAsString();+?></pre>
++++++++<?+endif;+?>
++++</body>
</html><?+//+back+in+php
}
set_exception_handler(+'global_exception_handler'+);

class+X
{
++++function+__construct()
++++{
++++++++trigger_error(+'Whoops!',+E_USER_NOTICE+);++++++
++++}
}

$x+=+new+X();

throw+new+Exception(+'Execution+will+never+get+here'+);

?>|code-block|syntax|javascript|1347730|entityMap|0|LINK|mutability|MUTABLE|url|//php.net/set_error_handler|1|//php.net/file_get_contents^0|3|H|1P|I|3|H|0|1P|I|1|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]|$9|18|A|19|1|1A]]|E|$]]|$1|F|3|G|5|6|7|1B|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|1C|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|1D|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|1E|8|@]|D|@]|E|$O|P]]|$1|Q|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]]]

<p>I usually <a href="//php.net/set_error_handler" rel="nofollow noreferrer"><code>set_error_handler</code></a> to a function that takes the error and throws an exception so that whatever happens i'll just have exceptions to deal with. No more <a href="//php.net/file_get_contents" rel="nofollow noreferrer"><code>@file_get_contents</code></a> just nice and neat try/catch.</p>
<p>In debug situations i also have an exception handler that outputs an asp.net like page. I'm posting this on the road but if requested I will post example source later.</p>
<p>edit:</p>
<p>Addition as promised, I've cut and pasted some of my code together to make a sample.</p>
<pre><code>&lt;?php

define( 'DEBUG', true );

class ErrorOrWarningException extends Exception
{
    protected $_Context = null;
    public function getContext()
    {
        return $this-&gt;_Context;
    }
    public function setContext( $value )
    {
        $this-&gt;_Context = $value;
    }
    
    public function __construct( $code, $message, $file, $line, $context )
    {
        parent::__construct( $message, $code );

        $this-&gt;file = $file;
        $this-&gt;line = $line;
        $this-&gt;setContext( $context );
    }
}

/**
 * Inspire to write perfect code. everything is an exception, even minor warnings.
 **/
function error_to_exception( $code, $message, $file, $line, $context )
{
    throw new ErrorOrWarningException( $code, $message, $file, $line, $context );
}
set_error_handler( 'error_to_exception' );

function global_exception_handler( $ex )
{
    ob_start();
    dump_exception( $ex );
    $dump = ob_get_clean();
    // send email of dump to administrator?...

    // if we are in debug mode we are allowed to dump exceptions to the browser.
    if ( defined( 'DEBUG' ) &amp;&amp; DEBUG == true )
    {
        echo $dump;
    }
    else // if we are in production we give our visitor a nice message without all the details.
    {
        echo file_get_contents( 'static/errors/fatalexception.html' );
    }
    exit;
}

function dump_exception( Exception $ex )
{
    $file = $ex-&gt;getFile();
    $line = $ex-&gt;getLine();

    if ( file_exists( $file ) )
    {
        $lines = file( $file );
    }
    
?&gt;&lt;html&gt;
    &lt;head&gt;
        &lt;title&gt;&lt;?= $ex-&gt;getMessage(); ?&gt;&lt;/title&gt;
        &lt;style type=&quot;text/css&quot;&gt;
            body {
                width : 800px;
                margin : auto;
            }
        
            ul.code {
                border : inset 1px;
            }
            ul.code li {
                white-space: pre ;
                list-style-type : none;
                font-family : monospace;
            }
            ul.code li.line {
                color : red;
            }
            
            table.trace {
                width : 100%;
                border-collapse : collapse;
                border : solid 1px black;
            }
            table.thead tr {
                background : rgb(240,240,240);
            }
            table.trace tr.odd {
                background : white;
            }
            table.trace tr.even {
                background : rgb(250,250,250);
            }
            table.trace td {
                padding : 2px 4px 2px 4px;
            }
        &lt;/style&gt;
    &lt;/head&gt;
    &lt;body&gt;
        &lt;h1&gt;Uncaught &lt;?= get_class( $ex ); ?&gt;&lt;/h1&gt;
        &lt;h2&gt;&lt;?= $ex-&gt;getMessage(); ?&gt;&lt;/h2&gt;
        &lt;p&gt;
            An uncaught &lt;?= get_class( $ex ); ?&gt; was thrown on line &lt;?= $line; ?&gt; of file &lt;?= basename( $file ); ?&gt; that prevented further execution of this request.
        &lt;/p&gt;
        &lt;h2&gt;Where it happened:&lt;/h2&gt;
        &lt;? if ( isset($lines) ) : ?&gt;
        &lt;code&gt;&lt;?= $file; ?&gt;&lt;/code&gt;
        &lt;ul class=&quot;code&quot;&gt;
            &lt;? for( $i = $line - 3; $i &lt; $line + 3; $i ++ ) : ?&gt;
                &lt;? if ( $i &gt; 0 &amp;&amp; $i &lt; count( $lines ) ) : ?&gt;
                    &lt;? if ( $i == $line-1 ) : ?&gt;
                        &lt;li class=&quot;line&quot;&gt;&lt;?= str_replace( &quot;\n&quot;, &quot;&quot;, $lines[$i] ); ?&gt;&lt;/li&gt;
                    &lt;? else : ?&gt;
                        &lt;li&gt;&lt;?= str_replace( &quot;\n&quot;, &quot;&quot;, $lines[$i] ); ?&gt;&lt;/li&gt;
                    &lt;? endif; ?&gt;
                &lt;? endif; ?&gt;
            &lt;? endfor; ?&gt;
        &lt;/ul&gt;
        &lt;? endif; ?&gt;

        &lt;? if ( is_array( $ex-&gt;getTrace() ) ) : ?&gt;
        &lt;h2&gt;Stack trace:&lt;/h2&gt;
            &lt;table class=&quot;trace&quot;&gt;
                &lt;thead&gt;
                    &lt;tr&gt;
                        &lt;td&gt;File&lt;/td&gt;
                        &lt;td&gt;Line&lt;/td&gt;
                        &lt;td&gt;Class&lt;/td&gt;
                        &lt;td&gt;Function&lt;/td&gt;
                        &lt;td&gt;Arguments&lt;/td&gt;
                    &lt;/tr&gt;
                &lt;/thead&gt;
                &lt;tbody&gt;
                &lt;? foreach ( $ex-&gt;getTrace() as $i =&gt; $trace ) : ?&gt;
                    &lt;tr class=&quot;&lt;?= $i % 2 == 0 ? 'even' : 'odd'; ?&gt;&quot;&gt;
                        &lt;td&gt;&lt;?= isset($trace[ 'file' ]) ? basename($trace[ 'file' ]) : ''; ?&gt;&lt;/td&gt;
                        &lt;td&gt;&lt;?= isset($trace[ 'line' ]) ? $trace[ 'line' ] : ''; ?&gt;&lt;/td&gt;
                        &lt;td&gt;&lt;?= isset($trace[ 'class' ]) ? $trace[ 'class' ] : ''; ?&gt;&lt;/td&gt;
                        &lt;td&gt;&lt;?= isset($trace[ 'function' ]) ? $trace[ 'function' ] : ''; ?&gt;&lt;/td&gt;
                        &lt;td&gt;
                            &lt;? if( isset($trace[ 'args' ]) ) : ?&gt;
                                &lt;? foreach ( $trace[ 'args' ] as $i =&gt; $arg ) : ?&gt;
                                    &lt;span title=&quot;&lt;?= var_export( $arg, true ); ?&gt;&quot;&gt;&lt;?= gettype( $arg ); ?&gt;&lt;/span&gt;
                                    &lt;?= $i &lt; count( $trace['args'] ) -1 ? ',' : ''; ?&gt; 
                                &lt;? endforeach; ?&gt;
                            &lt;? else : ?&gt;
                            NULL
                            &lt;? endif; ?&gt;
                        &lt;/td&gt;
                    &lt;/tr&gt;
                &lt;? endforeach;?&gt;
                &lt;/tbody&gt;
            &lt;/table&gt;
        &lt;? else : ?&gt;
            &lt;pre&gt;&lt;?= $ex-&gt;getTraceAsString(); ?&gt;&lt;/pre&gt;
        &lt;? endif; ?&gt;
    &lt;/body&gt;
&lt;/html&gt;&lt;? // back in php
}
set_exception_handler( 'global_exception_handler' );

class X
{
    function __construct()
    {
        trigger_error( 'Whoops!', E_USER_NOTICE );      
    }
}

$x = new X();

throw new Exception( 'Execution will never get here' );

?&gt;
</code></pre>


blocks|key|1563336|text|一旦定义了set_error_handler()，错误处理程序就类似于Exception的处理程序。请参阅以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1563337|+<?php
+function+handleErrors(+$e_code+)+{
+++echo+"error+code:+"+.+$e_code+.+"<br>";
+}

+set_error_handler(+"handleErrors"+);+

+trigger_error(+"trigger+a+fatal+error",+E_USER_ERROR);
+echo+"after+error.";+//it+would+run+if+set_error_handler+is+defined,+otherwise,+it+wouldn't+show
?>|code-block|syntax|javascript|1563338|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>Once set_error_handler() is defined, error handler is similar to Exception's. See code below:</p>

<pre><code> &lt;?php
 function handleErrors( $e_code ) {
   echo "error code: " . $e_code . "&lt;br&gt;";
 }

 set_error_handler( "handleErrors" ); 

 trigger_error( "trigger a fatal error", E_USER_ERROR);
 echo "after error."; //it would run if set_error_handler is defined, otherwise, it wouldn't show
?&gt;
</code></pre>


blocks|key|1347921|text|我想你要找的答案是；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1347922|错误是你习惯的标准东西，比如回显一个不存在的$variable。|1347923|只有在PHP5之后才会出现异常，并且是在处理对象时出现的。|1347924|要保持简单，请执行以下操作：|1347925|异常是您在处理对象时遇到的错误。try/catch语句允许您对它们执行一些操作，它的用法与if/else语句非常相似。试着这样做，如果有问题，没有关系，就这样做。|1347926|如果你没有“捕捉”到一个异常，那么它就会变成一个标准错误。|1347927|错误是php的基本错误，通常会中止你的脚本。|1347928|Try/catch通常用于建立像PDO这样的数据库连接，如果您想要重定向脚本或在连接不起作用时执行其他操作，这是很好的。但是，如果您只想显示错误消息并停止脚本，那么您就不需要它，未捕获的异常会变成致命错误。或者，您也可以使用站点范围的错误处理设置。|1347929|希望这能有所帮助|1347930|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|X|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|Y|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|Z|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|10|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|11|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|S|$]]

<p>I think the anwser you're looking for is that;  </p>

<p>Errors are the standard stuff you're used to, like echoing a $variable that doesnt exist.<br>
Exceptions are only from PHP 5 onwards and come when dealing with objects.</p>

<p>To keep it simple:</p>

<p>Exceptions are the errors you get when dealing with objects. 
The try/catch statement lets you do something about them though, and is used much like the if/else statement. 
Try to do this, if problem, doesnt matter, do this.</p>

<p>If you dont "catch" an exception, then it turns into a standard error.</p>

<p>Errors are the php fundemental errors which usually halt your script. </p>

<p>Try/catch is often used for establishing database connections like PDO, which is fine if you want to redirect the script or do something else if the connection doesnt work. But if you just want to display the error message and stop the script then you dont need it, the uncaught exception turns into a fatal error. Or you can use a site-wide error handling setting as well.</p>

<p>Hope that helps</p>


blocks|key|1348029|text|我打算给你一个关于错误控制的最不寻常的讨论。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1348030|几年前，我在一门语言中构建了一个非常好的错误处理程序，尽管其中一些名称发生了变化，但错误处理的原则在今天是相同的。我有一个定制的多任务操作系统，必须能够从所有级别的数据错误中恢复，而不会出现内存泄漏、堆栈增长或崩溃。因此，下面是我对错误和异常必须如何操作以及它们之间的区别的理解。我只能说，我不了解try+catch的内部是如何工作的，所以我在某种程度上是猜测的。|1348031|错误处理发生的第一件事就是从一个程序状态跳到另一个程序状态。这是怎么做到的呢？我会讲到那个的。|1348032|从历史上看，错误更老、更简单，而异常则更新、更复杂、更有能力。错误可以很好地工作，直到你需要把它们泡泡起来，这相当于把一个棘手的问题交给了你的主管。|1348033|错误可以是数字，如错误号，有时还可以包含一个或多个相关字符串。例如，如果发生文件读取错误，您可以报告它是什么，并可能正常地失败。(嘿，它不像过去那样只是崩溃了一步。)|1348034|关于异常，人们不常说的是，异常是位于特殊异常堆栈上的对象。它类似于程序流的返回堆栈，但它只为错误尝试和捕获保存返回状态。(我过去称它们为ePush和ePop，Abort是一个有条件的抛出，它将ePop并恢复到那个级别，而Abort是一个完全死亡或退出。)|1348035|堆栈的底部是有关初始调用者的信息，该对象知道启动外部try时的状态，这通常是程序启动时的状态。在上面，或者说堆栈的下一层，up是子对象，down是父对象，是下一个内部try/catch块的异常对象。|1348036|如果你把try放在try里面，你就把内部try堆在了外层try上面。当在内部try中发生错误并且内部catch不能处理它或者错误被抛出到外部try时，则将控制权传递给外部catch块(对象)以查看它是否可以处理该错误，即您的主管。|1348037|因此，这个错误堆栈真正做的是能够标记和恢复程序流和系统状态，换句话说，它允许程序在出错时不会使返回堆栈崩溃，也不会给其他人(数据)造成混乱。因此，它还保存任何其他资源的状态，如内存分配池，以便在捕获完成时清理它们。一般来说，这可能是一件非常复杂的事情，这就是为什么异常处理通常很慢的原因。一般来说，相当多的状态需要进入这些异常块中。|1348038|因此，try/catch块在某种程度上设置了一种状态，以便在其他一切都搞乱的情况下能够返回。就像父母一样。当我们的生活一团糟时，我们可以回到父母的怀抱，他们会让一切恢复正常。|1348039|希望我没让你失望。|1348040|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Z|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|10|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|11|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|12|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|13|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|14|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|15|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|16|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|17|8|@]|9|@]|A|$]]|$1|V|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|W|$]]

<p>I intend to give you a most unusual discussion of error control.</p>

<p>I built a very good error handler into a language years ago, and though some of the names have changed, the principles of error processing are the same today.  I had a custom built multi-tasking OS and had to be able to recover from data errors at all levels with no memory leaks, stack growth or crashes.  So what follows is my understanding of how errors and exceptions must operate and how they differ.  I will just say I do not have an understanding of how the internals of try catch works, so am guessing to some measure.</p>

<p>The first thing that happens under the covers for error processing is jumping from one program state to another.  How is that done?  I'll get to that.</p>

<p>Historically, errors are older and simpler, and exceptions are newer and a bit more complex and capable.  Errors work fine until you need to bubble them up, which is the equivalent of handing a difficult problem to your supervisor.</p>

<p>Errors can be numbers, like error numbers, and sometimes with one or more associated strings.  For example if a file-read error occurs you might be able to report what it is and possibly gracefully fail.  (Hay, it's a step up from just crashing like in the old days.)</p>

<p>What is not often said about exceptions is that exceptions are objects layered on a special exception stack.  It's like a return stack for program flow, but it holds a return state just for error trys and catches.  (I used to call them ePush and ePop, and ?Abort was a conditional throw which would ePop and recover to that level, while Abort was a full die or exit.)</p>

<p>On the bottom of the stack is the information about the initial caller, the object that knows about the state when the outer try was started, which is often when your program was started.  On top that, or the next layer on the stack, with up being the children, and down being the parents, is the exception object of the next inner try/catch block.</p>

<p>If you put a try inside a try you are stacking the inner try on top of the outer try.  When an error occurs in the inner try and either the inner catch can't handle it or the error is thrown to the outer try, then control is passed to the outer catch block (object) to see if it can handle the error, i.e. your supervisor.</p>

<p>So what this error stack really does is to be able to mark and restore program flow and system state, in other words, it allows a program to not crash the return stack and mess up things for others (data) when things go wrong.  So it also saves the state of any other resources like memory allocation pools and so it can clean them up when catch is done.  In general this can be a very complicated thing, and that is why exception handling is often slow.  In general quite a bit of state needs to go into these exception blocks.</p>

<p>So a try/catch block sort of sets a state to be able to return to if all else gets messed up.  It's like a parent.  When our lives get messed up we can fall back into our parent's lap and they will make it all right again.</p>

<p>Hope I didn't disappoint you.</p>


blocks|key|1563597|text|正如在其他答案中所述，将错误处理程序设置为异常抛出程序是处理PHP中错误的最佳方法。我使用了一个更简单的设置：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1563598|set_error_handler(function+($errno,+$errstr,+$errfile,+$errline+)+{
++++++++if+(error_reporting())+{
++++++++++++++++throw+new+\ErrorException($errstr,+0,+$errno,+$errfile,+$errline);
++++++++}
});|code-block|syntax|javascript|1563599|请注意保持@操作员正常工作的error_reporting()检查。此外，也不需要定义自定义异常，PHP有一个很好的类。|offset|length|style|CODE|1563600|抛出异常的最大好处是异常具有与其关联的堆栈跟踪，因此很容易找到问题所在。|1563601|entityMap^0|0|0|5|1|E|H|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

<p>As stated in other answers, setting error handler to exception thrower is the best way to handle errors in PHP. I use a bit simpler setup:</p>

<pre><code>set_error_handler(function ($errno, $errstr, $errfile, $errline ) {
        if (error_reporting()) {
                throw new \ErrorException($errstr, 0, $errno, $errfile, $errline);
        }
});
</code></pre>

<p>Please note the <code>error_reporting()</code> check to keep <code>@</code> operator working. Also, there is no need to define custom exception, PHP has one nice class for that.</p>

<p>Great benefit of throwing exceptions is that exception has stack trace associated with them, so it is easy to find where is the problem.</p>


blocks|key|1563630|text|您可以添加此评论|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1563631|function+doSomething()
{
+++/**+@noinspection+PhpUnhandledExceptionInspection+*/
+++throw+new+Exception();
}|code-block|syntax|javascript|1563632|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

<p>You may add this comment </p>

<pre><code>function doSomething()
{
   /** @noinspection PhpUnhandledExceptionInspection */
   throw new Exception();
}
</code></pre>


<p>Maybe I'm missing it somewhere in the PHP manual, but what exactly is the difference between an error and an exception?  The only difference that I can see is that errors and exceptions are handled differently.  But what causes an exception and what causes an error?</p>


PHP: exceptions vs errors?

数据库

也许我在PHP手册的某个地方遗漏了它，但是错误和异常到底有什么区别呢？我能看到的唯一区别是错误和异常的处理方式不同。但是是什么导致了异常，又是什么导致了错误呢？

问PHP:异常与错误？
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问PHP:异常与错误？EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问PHP:异常与错误？
EN