blocks|key|159205|text|您需要多次调用isset，每个参数对应一个要检查的参数！|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|159206|请记住，or与%7C%7C具有不同的优先级，您通常需要后者。|159207|您会得到一个解析错误，因为您将复合表达式传递给了isset，而不是变量。它不是一个常规函数，而是一个单独的语言结构，这就是为什么它有自己的任意规则，正如文档所指出的那样：|159208|159209|+isset()只适用于变量，因为传递其他任何参数都会导致解析错误。|blockquote|159210|159211|159212|159213|也许您认为PHP模仿了自然语言，因此您将其理解为"Is+input+or+input2+or+input3+set?"。|159214|这将是一种误解。如果它在语法上是有效的，它将首先在逻辑上将这些值OR在一起，然后将该值传递给isset-by，此时，与您的变量的所有连接都将丢失，剩下的只有true或false，然后将对其应用isset。|159215|entityMap^0|7|5|0|4|2|7|2|0|O|5|0|0|0|0|0|0|O|Z|0|W|2|1A|5|26|4|2B|5|2O|5|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|17|8|@]|D|@]|E|$]]|$1|K|3|L|5|M|7|18|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|19|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1C|8|@$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|1F|8|@$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1Q|8|@]|D|@]|E|$]]]|V|$]]

You need to make multiple calls to <code>isset</code>, one for every parameter you want to check!

Keep in mind that <code>or</code> has a different precedence from <code>||</code>, you usually want the latter.

You get a parse error because you pass a compound expression to <code>isset</code> and not a variable. It's not a regular function, but a separate language construct which is why it has its own arbitrary rules as pointed out by the docs:

<blockquote>
 isset() only works with variables as passing anything else will result in a parse error. 
</blockquote>

<hr>

Perhaps you think that PHP emulates natural languages and you therefore read it as <code>"Is input or input2 or input3 set?"</code>.

That would be a misconception. If it were valid syntactically, it would logically <code>OR</code> the values together at first, and then it would pass that one value to <code>isset</code>&mdash;by that time, all connection to your variables is lost and the only thing that is left is either <code>true</code> or <code>false</code> onto which <code>isset</code> would then be applied.

blocks|key|4620723|text|if(isset($_GET['input'])+%7C%7C+isset($_GET['input2'])+%7C%7C+isset($_GET['input3']))|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4620724|但实际上我认为这里需要的是AND，而不是OR，所以如果我是正确的，请将%7C%7C更改为&&。|unstyled|4620725|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(isset($_GET['input']) || isset($_GET['input2']) || isset($_GET['input3']))
</code></pre>

But I actually think you need AND here, not OR, so change || to &amp;&amp; if I am correct.

blocks|key|4620751|text|您必须为每个参数分别调用isset。isset()接受单个参数并相应地响应。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4620752|有关更多详细信息，请查看isset。|4620753|sql提示：如果您在数据库查询中使用这些变量，则必须使用mysqli_real_escape_string()来避免可能的注入|BOLD|4620754|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.isset.php|1|http://php.net/manual/en/mysqli.real-escape-string.php^0|C|5|I|7|0|C|5|0|0|1P|2|S|R|1|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@$9|10|A|11|1|12]]|E|$]]|$1|H|3|I|5|6|7|13|8|@$9|14|A|15|B|J]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|K|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]|S|$5|N|O|P|E|$Q|T]]]]

You have to call <code>isset</code> for each parameter separately. <code>isset()</code> accepts single parameter and respond accordingly..

For more details check <a href="http://php.net/manual/en/function.isset.php" rel="nofollow">isset</a>.

Bonus Tip:
If you are using these variables in database queries, you must use <a href="http://php.net/manual/en/mysqli.real-escape-string.php" rel="nofollow">mysqli_real_escape_string()</a> to avoid possible sql injection

blocks|key|788475|text|目前对这个问题的所有答案都忽略了isset的一个重要特性:它可以同时检查多个变量。来自the+manual|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|788476|如果提供了多个参数，则|788477|+()仅在设置了所有参数时才返回TRUE。求值从左到右进行，遇到未设置的变量时立即停止。|blockquote|788478|788479|788480|所以在这种情况下，你可以这样做：|788481|if+(isset($_GET['input'],+$_GET['input2'],+$_GET['input3']))+{|code-block|syntax|javascript|788482|只有在设置了所有_GET元素的情况下，此条件才会通过。|788483|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.isset.php^0|G|5|17|A|0|0|0|0|0|0|0|0|8|4|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$]]|$1|K|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1D|8|@]|D|@]|E|$]]|$1|O|3|P|5|Q|7|1E|8|@]|D|@]|E|$R|S]]|$1|T|3|U|5|6|7|1F|8|@$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|V|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|W|$X|$5|Y|Z|10|E|$11|12]]]]

All the current answers to this question miss an important feature of <code>isset</code>: it can check for multiple variables at the same time. From <a href="http://php.net/manual/en/function.isset.php" rel="nofollow">the manual</a>:

<blockquote>
 If multiple parameters are supplied then isset() will return TRUE only if all of the parameters are set. Evaluation goes from left to right and stops as soon as an unset variable is encountered. 
</blockquote>

So in this case you can do something like this:

<pre><code>if (isset($_GET['input'], $_GET['input2'], $_GET['input3'])) {
</code></pre>

This conditional will only pass if all the <code>_GET</code> elements are set.

blocks|key|159248|text|这将修复您的错误：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|159249|if(isset($_GET['input'])+or+isset($_GET['input2'])+or+isset($_GET['input3']))
{
++++$release=$_GET['input'].$_GET['input2'].$_GET['input3'];
++++echo+$release;
}|code-block|syntax|javascript|159250|但是因为您测试的是OR而不是AND，所以您只需要其中一个OR测试返回true就可以进入if条件-如果其他两个测试中的任何一个未设置，您仍然会抛出通知/错误。|159251|要检查这三种方法是否都存在，您可以执行如下操作|159252|if+(isset($_GET['input'])+&&+isset($_GET['input2'])+&&+isset($_GET['input3']))+{+
++++//...
}|159253|这可能会实现您想要实现的目标，而不会出现混乱的测试：|159254|//+count+will+return+however+many+key=>val+pairs+are+in+the+array,+
//+0+will+fail
if+(count($_GET))+{
++++//+an+empty+array+and+an+empty+string+to+hold+iterated+results
++++$get+=+array();
++++$release+=+'';
++++//+iterate+through+$_GET+and+append+each+key=>val+pair+to+the+local+array,+
++++//+then+concat+onto+the+string
++++foreach($_GET+as+$key=>$val)+{
++++++++$get[$key]+=+$val;
++++++++$release+.=+$get[$key];
++++}
++++echo+$release;
}|159255|HTH+:)|159256|159257|编辑:正如其他人所指出的，如果您需要测试以确保设置了所有这些数组键，请跳过foreach循环，只需执行以下操作：|offset|length|style|CODE|159258|+//+extract+imports+all+of+the+array+keys+into+the+symbol+table.+
+//+It+returns+the+number+of+symbls+imported,+and+automatically
+//+sets+vars+using+keys+for+var+name:+
+if+(extract($_GET)+&&+isset($input,$input2,$input3))+{
+++++echo+$release+=+$input.$input2.$input3;
+}|159259|(使用传递给isset的多个参数。)|159260|159261|HTH+:)|unordered-list-item|159262|159263|entityMap^0|0|0|0|0|0|0|0|0|0|11|7|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|1D|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|1E|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|1F|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|1G|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1H|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|1J|8|@$V|1K|W|1L|X|Y]]|9|@]|A|$]]|$1|Z|3|10|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|11|3|12|5|6|7|1N|8|@]|9|@]|A|$]]|$1|13|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]|$1|14|3|15|5|16|7|1P|8|@]|9|@]|A|$]]|$1|17|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|18|3|-4|5|6|7|1R|8|@]|9|@]|A|$]]]|19|$]]

This will fix your error:

<pre><code>if(isset($_GET['input']) or isset($_GET['input2']) or isset($_GET['input3']))
{
 $release=$_GET['input'].$_GET['input2'].$_GET['input3'];
 echo $release;
}
</code></pre>

But because you're testing OR instead of AND, all you would need is 1 of those OR tests to come back true to get into the if condition - and if either of the other 2 were unset, you'd still throw a notice / error.

To check that all three exist, you'd do something like

<pre><code>if (isset($_GET['input']) &amp;&amp; isset($_GET['input2']) &amp;&amp; isset($_GET['input3'])) { 
 //...
}
</code></pre>

This probably does what you're trying to achieve without the messy test: 

<pre><code>// count will return however many key=&gt;val pairs are in the array, 
// 0 will fail
if (count($_GET)) {
 // an empty array and an empty string to hold iterated results
 $get = array();
 $release = '';
 // iterate through $_GET and append each key=&gt;val pair to the local array, 
 // then concat onto the string
 foreach($_GET as $key=&gt;$val) {
 $get[$key] = $val;
 $release .= $get[$key];
 }
 echo $release;
}
</code></pre>

HTH :)

<hr>

EDIT: As others indicated, if you need the test to ensure all of those array keys are set, skip the <code>foreach</code> loop and just do this:

<pre><code> // extract imports all of the array keys into the symbol table. 
 // It returns the number of symbls imported, and automatically
 // sets vars using keys for var name: 
 if (extract($_GET) &amp;&amp; isset($input,$input2,$input3)) {
 echo $release = $input.$input2.$input3;
 }
</code></pre>

(Using multiple arguments passed to isset.)

<ul>
<li>HTH :)</li>
</ul>

Hi can someone help me on what i have done wrong in my conditional statement.

<pre><code>if(isset($_GET['input'] or $_GET['input2'] or $_GET['input3']))
{
 $release=$_GET['input'].$_GET['input2'].$_GET['input3'];
 echo $release;
}
</code></pre>

EDIT: ERROR IS <code>syntax error, unexpected T_LOGICAL_OR, expecting ',' or ')'</code>

PHP conditional statement

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。

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嗨，有人能帮我解决我在条件语句中做错了什么吗？if(isset($_GET['input'] or $_GET['input2'] or $_GET['input3'])){  $release=$_GET['input'].$_GET['input2'].$_GET['input3'];  echo $release;}编辑:错误为syntax error, unexpected T_LOGIC

问PHP条件语句
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