blocks|key|2973777|text|如果您遵循的是面向对象的方法，那么异常对于错误处理就很方便。通过异常跨对象传递错误是很方便的。如果你使用分层设计方法，异常是非常有用的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2973778|如果你不是以面向对象的方式编码，那么就不需要异常。|2973779|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|$]]

If you are following the object-oriented methodology then exceptions comes handy for the error handling. It is convenient to communicate the errors through exception across the objects.
Exceptions are really helpful if you go with layered design approach. 

If you are not coding in object-oriented way, then exceptions are not required.

blocks|key|1358964|text|一般来说，使用异常处理有两个很好的理由：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1358965|1358966|你现在可能总是知道哪里会发生异常--一些意想不到的事情可能会出现。如果您使用全局异常处理程序，则可以确保无论发生什么错误，您的程序都有机会恢复。类似地，一段特别敏感的代码(比如执行I/O的代码)可能会有各种不同的错误，这些错误只能在运行时检测到，您需要捕获任何可能的意外情况。有些事情在测试过程中可能不会发生；例如，如果您控制之外的服务器出现故障怎么办？这可能永远不会在它真正发生之前被测试(尽管好的测试将包括这一点)。这是really.|ordered-list-item|1358967|Performance.更重要的原因通常情况下，只要没有出错，就会实现异常，所以一切都很快。异常在发生后被捕获。这意味着如果出现错误，没有'+if‘语句必须提前评估，并且在这种情况下开销非常低。如果你不使用异常，你将被迫在你的代码中添加很多'+If‘语句。虽然这通常不是什么大问题，但这可能会杀死一个性能关键型应用程序。这一点尤其正确，因为CPU中的分支预测错误可能会导致流水线刷新。|1358968|1358969|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|L|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|M|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|N|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|J|$]]

In general there are two good reasons to use exception handling:

<ol>
<li>You might now always know where an exception will occur - something unexpected could arise. If you use a global exception handler you can make sure that no matter what goes wrong, your program has a chance to recover. Similarly a particularly sensitive piece of code (like something that does I/O) could have all sorts of different errors that can only be detected at runtime and you want to catch any possible contingency. Some things might not occur during testing; like what if a server outside of your control fails? This may never be tested before it really happens (although good testing would include this). This is the more important reason really.</li>
<li>Performance. Typically exceptions are implemented so that everything is fast so long as nothing goes wrong. Exceptions are caught after they occur. This means that no 'if' statement has to be evaluated in advance if something goes wrong, and the overhead is very low in that case. If you don't use exceptions you will be forced to add a lot of 'if' statements to your code. While usually this isn't much of a problem, this can kill a performance-critical application. This is especially true because a branch mis-prediction in the CPU can cause a pipeline flush. </li>
</ol>

blocks|key|1359003|text|异常允许您区分不同类型的错误，并且对于路由也很有用。例如..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1359004|class+Application
{
++++public+function+run()
++++{
++++++++try+{
++++++++++++//+Start+her+up!!
++++++++}+catch+(Exception+$e)+{
++++++++++++//+If+Ajax+request,+send+back+status+and+message
++++++++++++if+($this->getRequest()->isAjax())+{
++++++++++++++++return+Application_Json::encode(array(
++++++++++++++++++++'status'+=>+'error',
++++++++++++++++++++'msg'++++=>+$e->getMessage());
++++++++++++}

++++++++++++//+...otherwise,+just+throw+error
++++++++++++throw+$e;
++++++++}
++++}
}|code-block|syntax|javascript|1359005|然后，引发的异常可以由自定义错误处理程序处理。|1359006|由于PHP是一种松散类型的语言，您可能需要确保只将字符串作为参数传递给类方法。例如..。|1359007|class+StringsOnly
{
++++public+function+onlyPassStringToThisMethod($string)
++++{
++++++++if+(!is_string($string))+{
++++++++++++throw+new+InvalidArgumentException('$string+is+definitely+not+a+string');
++++++++}

++++++++//+Cool+string+manipulation...

++++++++return+$this;
++++}
}|1359008|如果您需要以不同的方式处理不同类型的异常，请使用...or。|1359009|class+DifferentExceptionsForDifferentFolks
{
++++public+function+catchMeIfYouCan()
++++{
++++++++try+{
++++++++++++$this->flyForFree();
++++++++}+catch+(CantFlyForFreeException+$e)+{
++++++++++++$this->alertAuthorities();
++++++++++++return+'Sorry,+you+can\'t+fly+for+free+dude.+It+just+don\'t+work+that+way!';
++++++++}+catch+(DbException+$e)+{
++++++++++++//+Get+DB+debug+info
++++++++++++$this->logDbDebugInfo();
++++++++++++return+'Could+not+access+database.+What+did+you+mess+up+this+time?';
++++++++}+catch+(Exception+$e)+{
++++++++++++$this->logMiscException($e);
++++++++++++return+'I+catch+all+exceptions+for+which+you+did+not+account!';
++++++++}
++++}
}|1359010|如果在类似Zend+Framework的东西中使用事务：|1359011|class+CreditCardController+extends+Zend_Controller_Action
{
++++public+function+buyforgirlfriendAction()
++++{
++++++++try+{
++++++++++++$this->getDb()->beginTransaction();

++++++++++++$this->insertGift($giftName,+$giftPrice,+$giftWowFactor);

++++++++++++$this->getDb()->commit();
++++++++}+catch+(Exception+$e)+{
++++++++++++//+Error+encountered,+rollback+changes
++++++++++++$this->getDb()->rollBack();

++++++++++++//+Re-throw+exception,+allow+ErrorController+forward
++++++++++++throw+$e;
++++++++}
++++}
}|1359012|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

Exceptions allow you to distinguish between different types of errors, and is also great for routing. For example...

<pre><code>class Application
{
 public function run()
 {
 try {
 // Start her up!!
 } catch (Exception $e) {
 // If Ajax request, send back status and message
 if ($this-&gt;getRequest()-&gt;isAjax()) {
 return Application_Json::encode(array(
 'status' =&gt; 'error',
 'msg' =&gt; $e-&gt;getMessage());
 }

 // ...otherwise, just throw error
 throw $e;
 }
 }
}
</code></pre>

The thrown exception can then be handled by a custom error handler.

Since PHP is a loosely typed language, you might need to ensure that only strings are passed as arguments to a class method. For example...

<pre><code>class StringsOnly
{
 public function onlyPassStringToThisMethod($string)
 {
 if (!is_string($string)) {
 throw new InvalidArgumentException('$string is definitely not a string');
 }

 // Cool string manipulation...

 return $this;
 }
}
</code></pre>

...or if you need to handle different types of exceptions in different ways.

<pre><code>class DifferentExceptionsForDifferentFolks
{
 public function catchMeIfYouCan()
 {
 try {
 $this-&gt;flyForFree();
 } catch (CantFlyForFreeException $e) {
 $this-&gt;alertAuthorities();
 return 'Sorry, you can\'t fly for free dude. It just don\'t work that way!';
 } catch (DbException $e) {
 // Get DB debug info
 $this-&gt;logDbDebugInfo();
 return 'Could not access database. What did you mess up this time?';
 } catch (Exception $e) {
 $this-&gt;logMiscException($e);
 return 'I catch all exceptions for which you did not account!';
 }
 }
}
</code></pre>

If using transactions in something like Zend Framework:

<pre><code>class CreditCardController extends Zend_Controller_Action
{
 public function buyforgirlfriendAction()
 {
 try {
 $this-&gt;getDb()-&gt;beginTransaction();

 $this-&gt;insertGift($giftName, $giftPrice, $giftWowFactor);

 $this-&gt;getDb()-&gt;commit();
 } catch (Exception $e) {
 // Error encountered, rollback changes
 $this-&gt;getDb()-&gt;rollBack();

 // Re-throw exception, allow ErrorController forward
 throw $e;
 }
 }
}
</code></pre>

blocks|key|3259766|text|Exception+handling:+If+condition+versus+Exception并不是专门针对PHP的，但它提供了一个很好的视角。就我个人而言，Exception(s)+&+try/catch是用语言实现的，目的是在开发人员中强制执行良好的行为，而这些行为通常不会像错误检查/处理那样用心。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3259767|如果你确信你的if/else+if/else能捕捉到所有的场景，那就太酷了。|3259768|下面是Advantages+of+Exceptions+-+Java的概述--其中有一段代码，其中包含许多if/else语句和以下摘录：|3259769|3259770|这里有如此多的错误检测、报告和返回，以至于最初的7行代码在混乱中丢失了。更糟糕的是，代码的逻辑流也丢失了，因此很难判断代码是否在做正确的事情:如果函数没有分配足够的内存，文件真的会被关闭吗？当您在编写方法三个月后修改方法时，要确保代码继续执行正确的操作就更加困难了。许多程序员通过简单地忽略它来解决这个问题-当他们的程序崩溃时会报告错误。|blockquote|3259771|3259772|3259773|所以真的，归根结底是个人偏好。如果你想要代码是可读的，并且可以被其他人使用，这通常是一种更好的方法，并强制实现最佳行为|3259774|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/3572277/exception-handling-if-condition-versus-exception|1|http://download.oracle.com/javase/tutorial/essential/exceptions/advantages.htm^0|0|1D|0|0|0|3|V|1|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|D|3|E|5|6|7|13|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|H|3|-4|5|6|7|18|8|@]|9|@]|C|$]]|$1|I|3|J|5|K|7|19|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|1B|8|@]|9|@]|C|$]]|$1|N|3|O|5|6|7|1C|8|@]|9|@]|C|$]]|$1|P|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]]|Q|$R|$5|S|T|U|C|$V|W]]|X|$5|S|T|U|C|$V|Y]]]]

<a href="https://stackoverflow.com/questions/3572277/exception-handling-if-condition-versus-exception">Exception handling: If condition versus Exception</a> isn't specific to PHP, but gives a good perspective. Personally, Exception(s) &amp; try/catch are implemented in languages to enforce good behaviour amongst developers that normally wouldn't be as attentive to error checking / handling. 

If you are confident that your if/else if/else is catching all scenarios, than cool. 

Here is an overview of the <a href="http://download.oracle.com/javase/tutorial/essential/exceptions/advantages.htm" rel="nofollow noreferrer">Advantages of Exceptions - Java</a> -- At one point, there is a snippet of code that has many if/else statements and the following excerpt:

<blockquote>
 There's so much error detection, reporting, and returning here that the original seven lines of code are lost in the clutter. Worse yet, the logical flow of the code has also been lost, thus making it difficult to tell whether the code is doing the right thing: Is the file really being closed if the function fails to allocate enough memory? It's even more difficult to ensure that the code continues to do the right thing when you modify the method three months after writing it. Many programmers solve this problem by simply ignoring it — errors are reported when their programs crash.
</blockquote>

So really, it comes down to personal preference in the end. If you want code that is readable and can be consumed by other people, it's generally a better approach and enforces best-behaviour

blocks|key|3259801|text|拥有异常框架的主要原因之一是，如果代码到达无法继续执行的地步，它可以告诉周围的上下文出了问题。这意味着如果我有一个Foo类，它需要在$fooInstance->doFoo();成功之前调用$fooInstance->setBarHandler($barHandler)，这个类可以向更大的上下文提供一条消息，而不是静默地失败并返回FALSE。此外，它允许上下文说，“嗯，坏了。好了，我现在可以告诉用户/日志/其他事情发生了不好的事情，我可以决定我是否需要继续。”|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3259802|entityMap^0|1L|3|1U|M|2M|14|4L|5|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

One of the primary reasons for having an exceptions framework is so that if the code ever gets to the point where it cannot proceed, it has the ability to tell the surrounding context that something has gone wrong. It means that if I have a class <code>Foo</code> which needs to have <code>$fooInstance-&gt;setBarHandler($barHandler)</code> called before <code>$fooInstance-&gt;doFoo();</code> can succeed, the class can provide a message to the greater context instead of failing silently and returning <code>FALSE</code>. Further, it allows the context to say, "Huh. That broke. Well, I can now tell the user/logs/something else that something bad happened, and I can decide whether I need to keep on chugging."

blocks|key|2973962|text|如果我们不确定代码结果，我们会使用异常处理。我们将该代码片段放在try块中，并在catch块中捕获该错误。有关更多信息，请访问check+this+link。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2973963|entityMap|0|LINK|mutability|MUTABLE|url|http://www.w3schools.com/php/php_exception.asp^0|1R|F|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

We use exception handling if we are not sure about the code results. We put that snippet of code in try block and catch that error in catch block. Please <a href="http://www.w3schools.com/php/php_exception.asp" rel="nofollow">check this link</a> for more information.

blocks|key|2973997|text|与简单的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2973998|或false.|unordered-list-item|offset|length|style|CODE|2973999|
|2974000|Exceptions相比，-1异常可以提供更多的数据。请记住，try+..+catch块可以嵌套，并且在try+..+catch+block.|2974001|Exceptions中可能有多个catch块会强制您处理错误。当你不使用它们的时候，你可以这样做：|ordered-list-item|2974002|2974003|2974004|函数doSomething($a，$b，$c)+{+...if+($a+<+$b+&&+$b+>+$c)+{$a+-1；//错误}+...+}+$d+=+doSomething($x，$y，$z)；if+($d+===+-1)+{die(‘致命错误！’)；}|2974005|只要你记得检查函数是否返回错误，一切都是正常的。但是如果你忘记检查会发生什么呢？这实际上是一种非常常见的problem.|2974006|Exceptions，可以让程序的流程更加自然。|2974007|2974008|entityMap^0|0|1|5|0|0|D|2|V|C|1G|C|0|G|5|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@$E|12|F|13|G|H]]|9|@]|A|$]]|$1|I|3|J|5|6|7|14|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|15|8|@$E|16|F|17|G|H]|$E|18|F|19|G|H]|$E|1A|F|1B|G|H]]|9|@]|A|$]]|$1|M|3|N|5|O|7|1C|8|@$E|1D|F|1E|G|H]]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1F|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1H|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|1I|8|@]|9|@]|A|$]]|$1|V|3|W|5|D|7|1J|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|Z|$]]

<ol>
<li>Exceptions can provide much more data than simple <code>-1</code> or <code>false</code>.</li>
<li>Exceptions can do advanced error handling. Keep in mind that <code>try .. catch</code> blocks can be nested and there could be more than one <code>catch</code> block in <code>try .. catch</code> block.</li>
<li>Exceptions force you to handle errors. When you're not using them you do something like:

<pre><code>function doSomething($a, $b, $c) {
 ...

 if ($a &lt; $b &amp;&amp; $b &gt; $c) {
 return -1; // error
 }

 ...
}

$d = doSomething($x, $y, $z);

if ($d === -1) {
 die('Fatal error!');
}
</code></pre>

And everything is fine as long as you remember to check whether function returned error. But what happen if you forgot to check that? It's actually a quite common problem.</li>
<li>Exceptions make the flow of a program much more natural.</li>
</ol>

blocks|key|2974046|text|异常很难在正确的上下文中使用，特别是在php中。就我个人而言，当以下三种情况发生时，我会使用异常：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2974047|资源失败异常-当你的程序内存不足时，你可以抛出一个异常。例如，在php中，当你运行一个超过30秒的脚本时。尽管您可以在.ini中更改这一点|offset|length|style|BOLD|2974048|客户端代码错误、异常、-例如，当尝试使用错误的凭据连接到数据库或取消链接不在服务器上的文件时。或者，当数据库服务器关闭且无响应时，您可以抛出异常。|2974049|程序员错误异常-这些错误是由于您自己的编码而产生的，当您不确定您的代码将给您带来的结果时，也可以使用problems.This。例如，当除以0时。|2974050|entityMap^0|0|0|6|0|0|B|0|0|7|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|U|8|@$D|V|E|W|F|G]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|M|$]]

Exceptions are hard to use in the correct context,especially in php. Personally i use exceptions when these 3 things happen: 

Resource failure exception - You can throw an exception maybe when your program runs out of memory. for example in php when you run a script that exceeds 30 seconds executing. Though you can chanage that in .ini

Client code errors exceptions - For example when trying to connect to a database with the wrong credentials or unlinking a file not on server. Or when the database server is down and unresponsive, you can throw an exception.

Programmer error exception - These are errors generated due to your own coding problems.This can also be used when you are not sure of the results your code will give you. for example when dividing by 0.

I've been programming PHP for a long time, but not so much PHP 5... I've known about exception handling in PHP 5 for some time, but never really looked into it. After a quick Google it seems fairly pointless to use exception handling - I can't see the advantages of using it over just using some if() {} statements, and perhaps my own error handling class or whatever.

There's got to be a bunch of good reasons for using it (I guess?!) otherwise it wouldn't have been put into the language (probably). Can anyone tell me of some good benefits it has over just using a bunch of if statements or a switch statement or something?

Why should I use exception handling in php?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我已经编写PHP很长一段时间了，但不太喜欢PHP5……我知道PHP 5中的异常处理已经有一段时间了，但我从来没有真正研究过它。在快速搜索之后，使用异常处理似乎毫无意义-我看不出使用它比使用一些if() {}语句，或者我自己的错误处理类或其他什么使用它有什么好处。使用它肯定有一堆很好的理由(我猜？！)否则它就不会被放入语...

问为什么我要在php中使用异常处理？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问为什么我要在php中使用异常处理？EN