blocks|key|221437|text|if+($baz+==+0.0)+{
++++echo+'Divisor+is+0';
}+else+{
++++...
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|221438|如果您在回避的表达式中使用用户输入，那么为什么不使用像PHPClasses上的评价数学这样的正确的解析器，并在除以零的情况下引发一个干净的异常，而不是使用eval。|unstyled|offset|length|221439|entityMap|0|LINK|mutability|MUTABLE|url|http://www.phpclasses.org/package/2695-PHP-Safely-evaluate-mathematical-expressions.html^0|0|R|G|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>if ($baz == 0.0) {
 echo 'Divisor is 0';
} else {
 ...
}
</code></pre>

Rather than use eval, which is highly dangerous if you're using user-input within the evalled expression, why not use a proper parser such as <a href="http://www.phpclasses.org/package/2695-PHP-Safely-evaluate-mathematical-expressions.html" rel="noreferrer">evalmath on PHPClasses</a>, and which raises a clean exception on divide by zero

blocks|key|1771369|text|if(@eval("\$result+=+$expresion;")===FALSE){
++$result=0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1771370|但是不会被0除以错误。|unstyled|1771371|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>if(@eval("\$result = $expresion;")===FALSE){
 $result=0;
}
</code></pre>

Won't just catch divide by 0 errors though.

blocks|key|1417126|text|以下是另一个解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417127|<?php

function+e($errno,+$errstr,+$errfile,+$errline)+{
++++print+"caught!\n";
}

set_error_handler('e');

eval('echo+1/0;');|code-block|syntax|javascript|1417128|请参阅set_error_handler()|offset|length|style|CODE|1417129|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/set_error_handler^0|0|0|3|J|3|J|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@$I|Z|J|10|1|11]]|A|$]]|$1|M|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

Here's another solution:

<pre><code>&lt;?php

function e($errno, $errstr, $errfile, $errline) {
 print "caught!\n";
}

set_error_handler('e');

eval('echo 1/0;');
</code></pre>

See <a href="http://php.net/set_error_handler" rel="noreferrer"><code>set_error_handler()</code></a>

blocks|key|221478|text|使用@+(+差错控制算子.)这告诉php在发生错误时不要输出警告。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|221479|eval("\$result+=+@($expresion);");
if+($result+==+0)+{
++++//+do+division+by+zero+handling+
}+else+{
++++//+it's+all+good
}|code-block|syntax|javascript|221480|entityMap|0|LINK|mutability|MUTABLE|url|http://ca.php.net/manual/en/language.operators.errorcontrol.php^0|2|1|6|6|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Use a <code>@</code> (An <a href="http://ca.php.net/manual/en/language.operators.errorcontrol.php" rel="nofollow noreferrer">error control operator</a>.) This tells php to not output warnings in case of errors.

<pre><code>eval("\$result = @($expresion);");
if ($result == 0) {
 // do division by zero handling 
} else {
 // it's all good
}
</code></pre>

blocks|key|221515|text|正如其他人提到的，请考虑尝试一种解决方案，让您可以检查分母是否为0。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221516|由于您的目的似乎没有用，下面是PHP错误处理的一些背景知识。|221517|早期版本的PHP没有异常。相反，出现了不同级别的错误消息(通知、警告等)。致命错误将停止执行。|221518|PHP5给表带来了异常，新的(PDO)会在发生糟糕/意外的事情时抛出异常。最重要的是，核心代码库没有被重写为使用异常。核心功能和操作仍然依赖于旧的错误系统。|221519|如果除以0，则会收到警告，而不是例外。|221520|PHP+Warning:++Division+by+zero+in+/foo/baz/bar/test.php(2)+:+eval()'d+code+on+line+1
PHP+Stack+trace:
PHP+++1.+{main}()+/foo/baz/bar/test.php:0
PHP+++2.+eval()+/foo/baz/bar/test.php:2|code-block|syntax|javascript|221521|如果您想要“捕获”这些，您需要设置自定义错误处理程序来检测零错误的除法，并对它们做些什么。不幸的是，自定义错误处理程序是一个捕获器，这意味着您还需要编写一些代码来对所有其他错误执行适当的操作。|offset|length|221522|entityMap|0|LINK|mutability|MUTABLE|url|http://www.php.net/manual/en/function.set-error-handler.php^0|0|0|0|0|0|0|F|B|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|12|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|13|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|14|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|15|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|16|8|@]|9|@$Q|17|R|18|1|19]]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

As others have mentioned, consider trying a solution that will let you check if the denominator is 0.

Since that advice seems useless your purpose, here's a little background on PHP error handling.

Early versions of PHP didn't have exceptions. Instead, error messages of various levels were raised (Notices, Warnings, Etc). A Fatal error stops execution.

PHP5 brought exceptions to the table, and newer PHP provided libraries (PDO) will throw exceptions when bad/unexpected things happen. Hoever, the core codebase was NOT rewritten to use exception. Core functions and operations still rely on the old error system.

When you divide by 0, you get a Warning, not an exception

<pre><code>PHP Warning: Division by zero in /foo/baz/bar/test.php(2) : eval()'d code on line 1
PHP Stack trace:
PHP 1. {main}() /foo/baz/bar/test.php:0
PHP 2. eval() /foo/baz/bar/test.php:2
</code></pre>

If you want to "catch" these, you'll need to <a href="http://www.php.net/manual/en/function.set-error-handler.php" rel="nofollow noreferrer">set a custom error handler</a> that will detect division by zero errors and do something about them. Unfortunately, custom error handlers are a catch all, which means you'll also need to write some code to do something appropriate with all other errors.

blocks|key|1771434|text|我也面临着这个问题(动态表达)。我是那样做的，这可能不是最好的方法，但它是有效的。当然，您可以返回null或false或任何您希望的内容，而不是抛出异常。希望这能有所帮助。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1771435|function+eval_expression($expression)
{
++++ob_start();
++++eval('echo+('+.++$expression+.+');');
++++$result+=+ob_get_contents();
++++ob_end_clean();
++++if+(strpos($result,+'Warning:+Division+by+zero')!==false)
++++{
++++++++throw+new+Exception('Division+by+zero');
++++}
++++else+return+(float)$result;
}|code-block|syntax|javascript|1771436|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|$]]

I was facing that problem as well (dynamic expressions). Idid it that way which might not be the nicest way but it works. Instead of throwing an Exception you can of course return null or false or whatever you wish. Hope this helps.

<pre><code>function eval_expression($expression)
{
 ob_start();
 eval('echo (' . $expression . ');');
 $result = ob_get_contents();
 ob_end_clean();
 if (strpos($result, 'Warning: Division by zero')!==false)
 {
 throw new Exception('Division by zero');
 }
 else return (float)$result;
}
</code></pre>

blocks|key|1417241|text|包含数字和数学运算符%2B-*/的字符串作为输入传递。程序必须计算表达式的值(如BODMAS)并打印输出。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1417242|输入/输出示例:如果参数为"7+%2B+4*5“，则输出必须为27。如果参数为"55+%2B+21+*11-6/0“，则输出必须是"error”(因为没有定义零除法)。|1417243|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|$]]

A string containing numbers and the mathematical operators + - * / is passed as input.
The program must evaluate the value of the expression (as per BODMAS) and print the output.

Example Input/Output:
If the argument is "7 + 4*5" the output must be 27.
If the argument is "55 + 21 * 11 - 6/0" the output must be "error" (As division by zero is not defined).

blocks|key|1771460|text|您只需要设置一个错误处理程序就可以在发生错误时抛出异常：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1771461|set_error_handler(function+()+{
++++throw+new+Exception('Ach!');
});

try+{
++++$result+=+4+/+0;
}+catch(+Exception+$e+){
++++echo+"Divide+by+zero,+I+don't+fear+you!".PHP_EOL;
++++$result+=+0;
}

restore_error_handler();|code-block|syntax|javascript|1771462|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|$]]

You just need to set an error handler to throw an exception in case of errors:

<pre><code>set_error_handler(function () {
 throw new Exception('Ach!');
});

try {
 $result = 4 / 0;
} catch( Exception $e ){
 echo "Divide by zero, I don't fear you!".PHP_EOL;
 $result = 0;
}

restore_error_handler();
</code></pre>

blocks|key|221596|text|问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221597|b=1;+c=0;+a=b/c;+//+Error+Divide+by+zero|offset|length|style|CODE|221598|解决方案简单：|221599|if(c!=0)+a=b/c;
else+//+error+handling|code-block|syntax|javascript|221600|entityMap^0|0|0|14|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|U|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|V|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Problem:

<code>b=1; c=0;
a=b/c;
// Error Divide by zero</code>

Solution simple:

<pre><code>if(c!=0) a=b/c;
else // error handling
</code></pre>

blocks|key|1771511|text|我也一直在努力解决这个问题，set_error_handler解决方案不适合我，可能是基于。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1771512|对我来说，解决方案是尝试检测关机时的错误：|1771513|//+Since+set_error_handler+doesn't+catch+Fatal+errors,+we+do+this
function+shutdown()
{
++++$lastError+=+error_get_last();
++++if+(!empty($lastError))+{
++++++++$GLOBALS['logger']->debug(null,+$lastError);
++++}
}
register_shutdown_function('shutdown');|code-block|syntax|javascript|1771514|我不知道为什么除以0是关闭而不是由set_error_handler处理，但这帮助我超越它，只是默默地死去。|1771515|entityMap^0|E|H|0|0|0|H|H|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

I've been struggling with this too, the <code>set_error_handler</code> solutions were not working for me, probably based on PHP version differences.

The solution for me was to attempt to detect an error on shutdown:

<pre><code>// Since set_error_handler doesn't catch Fatal errors, we do this
function shutdown()
{
 $lastError = error_get_last();
 if (!empty($lastError)) {
 $GLOBALS['logger']-&gt;debug(null, $lastError);
 }
}
register_shutdown_function('shutdown');
</code></pre>

I'm not sure why a divide by 0 is shutting down rather than being handled by the <code>set_error_handler</code> but this helped me get beyond it just silently dying.

blocks|key|221683|text|在PHP7上，您可以使用DivisionByZeroError|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|221684|try+{
++++echo+1/0;
}+catch(DivisionByZeroError+$e){
++++echo+"got+$e";
}+catch(ErrorException+$e)+{
++++echo+"got+$e";
}|code-block|syntax|javascript|221685|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/class.divisionbyzeroerror.php^0|C|J|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

On PHP7 you can use <a href="http://php.net/manual/en/class.divisionbyzeroerror.php" rel="noreferrer">DivisionByZeroError</a>

<pre><code>try {
 echo 1/0;
} catch(DivisionByZeroError $e){
 echo "got $e";
} catch(ErrorException $e) {
 echo "got $e";
}
</code></pre>

blocks|key|1771597|text|我意识到这是一个古老的问题，但它是相关的今天，我真的不喜欢这里的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1771598|解决这个问题的正确方法是自己对表达式进行实际评估--即解析表达式，然后一步一步地对表达式进行评估，而不是将表达式转到PHP。这可以使用算法来完成。|offset|length|1771599|我编写了下面的实现，但我还没有对它进行测试。这是基于以上维基百科的文章。不支持右结合运算符，所以稍微简化了一些.|1771600|//+You+may+need+to+do+a+better+parsing+than+this+to+tokenize+your+expression.
//+In+PHP,+you+could+for+example+use+token_get_all()
$formula+=+explode('+',+'foo+%2B+bar+*+(+baz+/+(+foz+-+bak+)+)');;
$queue+=+array();
$operators+=+array();
$precedence+=+array('-'+=>+2,+'%2B'+=>+2,+'/'+=>+3,+'*'+=>+3,+'%5E'+=>+4);
$rightAssoc+=+array('%5E');
$variables+=+array('foo'+=>+$foo,+'bar'+=>+$bar,+'baz'+=>+$baz,+'foz'+=>+$foz,+'bak'+=>+$bak);

foreach($formula+as+$token)+{
++++if(isset($variables[$token]))+{
++++++++$queue[]+=+$variables[$token];
++++}+else+if(isset($precedence[$token]))+{
++++++++//+This+is+an+operator
++++++++while(
++++++++++++sizeof($operators)+>+0+&&+
++++++++++++$operators[sizeof($operators)-1]+!=++'('+&&+(
++++++++++++++++$precedence[$operators[sizeof($operators)-1]]+>+$precedence[$token]+%7C%7C
++++++++++++++++(
++++++++++++++++++++$precedence[$operators[sizeof($operators)-1]]+==+$precedence[$token]+&&
++++++++++++++++++++!in_array($operators[sizeof($operators)-1],+$rightAssoc)
++++++++++++++++)
++++++++++++)
++++++++)+$queue[]+=+array_pop($operators);
++++++++$operators[]+=+$token;
++++}+else+if($token+==+'(')+{
++++++++$operators[]+=+'(';
++++}+else+if($token+==+')')+{
++++++++while($operators[sizeof($operators)-1]+!=+'(')+{
++++++++++++$queue[]+=+array_pop($operators);
++++++++}
++++++++array_pop($operators);
++++}+else+if($token+==+')')+{
++++++++while($operators[sizeof($operators)-1]+!=+')')+{
++++++++++++$queue[]+=+array_pop($operators);
++++++++}
++++++++if(null+===+array_pop($operators))
++++++++++++throw+new+\Exception("Mismatched+parentheses");
}
$queue+=+array_merge($queue,+array_reverse($operators));
$stack+=+array();
foreach($queue+as+$token)+{
++++if(is_numeric($token))+$stack[]+=+$token;
++++else+switch($token)+{
++++++++case+'%2B'+:+
++++++++++++$stack[]+=+array_pop($stack)+%2B+array_pop($stack);
++++++++++++break;
++++++++case+'-'+:
++++++++++++//+Popped+variables+come+in+reverse,+so...
++++++++++++$stack[]+=+-array_pop($stack)+%2B+array_pop($stack);
++++++++++++break;
++++++++case+'*'+:
++++++++++++$stack[]+=+array_pop($stack)+*+array_pop($stack);
++++++++++++break;
++++++++case+'/'+:
++++++++++++$b+=+array_pop($stack);
++++++++++++$a+=+array_pop($stack);
++++++++++++if($b+==+0)
++++++++++++++++throw+new+\Exception("Division+by+zero");
++++++++++++$stack[]+=+$a+/+$b;
++++++++++++break;++++++++++++++++
++++}
}
echo+"The+result+from+the+calculation+is+".array_pop($stack)."\n";|code-block|syntax|javascript|1771601|(在您的特殊情况下)|style|BOLD|1771602|即使我更喜欢分流场的解决方案--如果我仍然决定使用eval()-version，我会创建一个custom_division($leftHandSide，$rightHandSide)方法，这会引发异常。此代码：|1771603|eval("$foo+%2B+$bar+*+(+$baz+/+(+$foz+-+$bak+)+)");|1771604|变成了|1771605|function+custom_division($a,+$b)+{+if($b+==+0)+throw+Exception("Div+by+0");+}
eval("$foo+%2B+$bar+*+(+custom_division(+$baz,+(+$foz+-+$bak+)+)");|1771606|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/Shunting-yard_algorithm^0|0|1V|2|0|0|0|0|0|A|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|F|3|G|5|6|7|1B|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1C|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1D|8|@$D|1E|E|1F|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1G|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|1H|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|1I|8|@]|9|@]|A|$]]|$1|W|3|X|5|J|7|1J|8|@]|9|@]|A|$K|L]]|$1|Y|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]]]

I realize this is an old question, but it is relevant today and I don't really like the answers here.

The proper way to fix this, is by actually evaluating the expression yourself - that is, by parsing the expression, then evaluating it step by step, instead of by transpiling it to PHP. This can be done using the <a href="https://en.wikipedia.org/wiki/Shunting-yard_algorithm" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Shunting-yard_algorithm</a>. 

I wrote the following implementation, but I haven't tested it. It's based on the above Wikipedia article. There is no support for right-associative operators, so it's slightly simplified.

<pre><code>// You may need to do a better parsing than this to tokenize your expression.
// In PHP, you could for example use token_get_all()
$formula = explode(' ', 'foo + bar * ( baz / ( foz - bak ) )');;
$queue = array();
$operators = array();
$precedence = array('-' =&gt; 2, '+' =&gt; 2, '/' =&gt; 3, '*' =&gt; 3, '^' =&gt; 4);
$rightAssoc = array('^');
$variables = array('foo' =&gt; $foo, 'bar' =&gt; $bar, 'baz' =&gt; $baz, 'foz' =&gt; $foz, 'bak' =&gt; $bak);

foreach($formula as $token) {
 if(isset($variables[$token])) {
 $queue[] = $variables[$token];
 } else if(isset($precedence[$token])) {
 // This is an operator
 while(
 sizeof($operators) &gt; 0 &amp;&amp; 
 $operators[sizeof($operators)-1] != '(' &amp;&amp; (
 $precedence[$operators[sizeof($operators)-1]] &gt; $precedence[$token] ||
 (
 $precedence[$operators[sizeof($operators)-1]] == $precedence[$token] &amp;&amp;
 !in_array($operators[sizeof($operators)-1], $rightAssoc)
 )
 )
 ) $queue[] = array_pop($operators);
 $operators[] = $token;
 } else if($token == '(') {
 $operators[] = '(';
 } else if($token == ')') {
 while($operators[sizeof($operators)-1] != '(') {
 $queue[] = array_pop($operators);
 }
 array_pop($operators);
 } else if($token == ')') {
 while($operators[sizeof($operators)-1] != ')') {
 $queue[] = array_pop($operators);
 }
 if(null === array_pop($operators))
 throw new \Exception("Mismatched parentheses");
}
$queue = array_merge($queue, array_reverse($operators));
$stack = array();
foreach($queue as $token) {
 if(is_numeric($token)) $stack[] = $token;
 else switch($token) {
 case '+' : 
 $stack[] = array_pop($stack) + array_pop($stack);
 break;
 case '-' :
 // Popped variables come in reverse, so...
 $stack[] = -array_pop($stack) + array_pop($stack);
 break;
 case '*' :
 $stack[] = array_pop($stack) * array_pop($stack);
 break;
 case '/' :
 $b = array_pop($stack);
 $a = array_pop($stack);
 if($b == 0)
 throw new \Exception("Division by zero");
 $stack[] = $a / $b;
 break; 
 }
}
echo "The result from the calculation is ".array_pop($stack)."\n";
</code></pre>

In your particular case

Even though I would prefer the Shunting Yard solution - if I still decided to go for an eval()-version, I would create a custom_division($leftHandSide, $rightHandSide) method, that throws an exception. This code:

<pre><code>eval("$foo + $bar * ( $baz / ( $foz - $bak ) )");
</code></pre>

becomes

<pre><code>function custom_division($a, $b) { if($b == 0) throw Exception("Div by 0"); }
eval("$foo + $bar * ( custom_division( $baz, ( $foz - $bak ) )");
</code></pre>

blocks|key|221723|text|使用intdiv和DivisionByZeroError|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|221724|try+{
++++$a+=+5;
++++$b+=+0;
++++intdiv($a,$b);
}
catch(DivisionByZeroError+$e){
++++echo+"got+{$e->getMessage()}";
}|code-block|syntax|javascript|221725|entityMap^0|2|6|9|J|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

using <code>intdiv</code> and <code>DivisionByZeroError</code>:

<pre><code>try {
 $a = 5;
 $b = 0;
 intdiv($a,$b);
}
catch(DivisionByZeroError $e){
 echo "got {$e-&gt;getMessage()}";
}
</code></pre>

blocks|key|1771637|text|这是我找到的实现这一目标的最佳方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1771638|error_clear_last();+//+Clear+any+previous+error
$result+=+@(1/0);+//+Executes+the+division,+suppressing+the+errors
$e+=+error_get_last();+//+Catches+the+last+error
if+($e+!==+null+&&+$e['message']+==+'Division+by+zero')+{
++++//+Division+by+zero+occurred,+do+something+here
}|code-block|syntax|javascript|1771639|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|$]]

This is the best way I found to accomplish this:

<pre><code>error_clear_last(); // Clear any previous error
$result = @(1/0); // Executes the division, suppressing the errors
$e = error_get_last(); // Catches the last error
if ($e !== null &amp;&amp; $e['message'] == 'Division by zero') {
 // Division by zero occurred, do something here
}
</code></pre>

blocks|key|221774|text|如果不需要额外的处理，您也可以这样做。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221775|$division+=+$foo+/+($bar+?:+1);|code-block|syntax|javascript|221776|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|$]]

If no additional handling is necessary you could also just do
<pre><code>$division = $foo / ($bar ?: 1);
</code></pre>

I have a large mathematical expression that has to be created dynamically. For example, once I have parsed "something" the result will be a string like: <code>"$foo+$bar/$baz";</code>.

So, for calculating the result of that expression I'm using the <code>eval</code> function... something like this:

<pre><code>eval("\$result = $expresion;");
echo "The result is: $result";
</code></pre>

The problem here is that sometimes I get errors that says there was a division by zero, and I don't know how to catch that Exception. I have tried things like:

<pre><code>eval("try{\$result = $expresion;}catch(Exception \$e){\$result = 0;}");
echo "The result is: $result";
</code></pre>

Or:

<pre><code>try{
 eval("\$result = $expresion;");
}
catch(Exception $e){
 $result = 0;
}
echo "The result is: $result";
</code></pre>

But it does not work. So, how can I avoid that my application crashes when there is a division by zero?

Edit:

First, I want to clarify something: the expression is built dynamically, so I can't just eval if the denominator is zero. So... with regards to the Mark Baker's comment, let me give you an example. My parser could build something like this:

<pre><code>"$foo + $bar * ( $baz / ( $foz - $bak ) )"
</code></pre>

The parser build the string step by step without worrying about the value of the vars... so in this case if <code>$foz == $bak</code> there's in fact a division by zero: <code>$baz / ( 0 )</code>.

On the other hand as Pete suggested, I tried:

<pre><code>&lt;?php
$a = 5;
$b = 0;

if(@eval(" try{ \$res = $a/$b; } catch(Exception \$e){}") === FALSE)
 $res = 0;
echo "$res\n";
?&gt; 
</code></pre>

But it does not print anything.

PHP, How to catch a division by zero?

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

我有一个很大的数学表达式，必须动态地创建。例如，一旦我解析了“某事”，结果将是一个字符串，如："$foo+$bar/$baz";。因此，为了计算表达式的结果，我使用了eval函数.就像这样：eval("\$result = $expresion;");echo "The result is: $result";这里的问...

问PHP，如何将一个除以零？
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PHP，如何将一个除以零？EN