blocks|key|413084|text|我不是PHP开发人员，但我认为您的第一种方法行不通。除了布尔值false之外，还有其他事情被解释为false：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|413085|When+converting+to+boolean,+the+following+values+are+considered+FALSE:

*+the+boolean+FALSE+itself
*+the+integer+0+(zero)
*+the+float+0.0+(zero)
*+the+empty+string,+and+the+string+"0"
*+an+array+with+zero+elements
*+an+object+with+zero+member+variables+(PHP+4+only)
*+the+special+type+NULL+(including+unset+variables)
*+SimpleXML+objects+created+from+empty+tags|code-block|syntax|javascript|413086|http://php.net/manual/en/language.types.boolean.php|offset|length|413087|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1F|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|T|8|@]|9|@$I|U|J|V|1|W]]|A|$]]|$1|K|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|H]]]]

I'm not a PHP developer, but I don't think your first approach works.
There are other things than the boolean value false interpreted as false:

<pre><code>When converting to boolean, the following values are considered FALSE:

* the boolean FALSE itself
* the integer 0 (zero)
* the float 0.0 (zero)
* the empty string, and the string "0"
* an array with zero elements
* an object with zero member variables (PHP 4 only)
* the special type NULL (including unset variables)
* SimpleXML objects created from empty tags
</code></pre>

<a href="http://php.net/manual/en/language.types.boolean.php" rel="nofollow">http://php.net/manual/en/language.types.boolean.php</a>

blocks|key|411864|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|411865|返回不同的数据类型是完全可以的。如果您想检查false，请使用:+if+($value+!==+false)。如果您弄丢了要使用的条件，这将澄清它：http://www.php.net/manual/en/types.comparisons.php|ordered-list-item|offset|length|411866|411867|entityMap|0|LINK|mutability|MUTABLE|url|http://www.php.net/manual/en/types.comparisons.php^0|0|22|1E|0|0|0^^$0|@$1|2|3|-4|4|5|6|O|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|P|7|@]|8|@$D|Q|E|R|1|S]]|9|$]]|$1|F|3|-4|4|5|6|T|7|@]|8|@]|9|$]]|$1|G|3|-4|4|5|6|U|7|@]|8|@]|9|$]]]|H|$I|$4|J|K|L|9|$M|N]]]]

<ol>
<li>It's perfectly OK to return different data types.</li>
<li>If you want to check against false, use: if ($value !== false). If you get lost which condition to use, this will clarify it: <a href="http://www.php.net/manual/en/types.comparisons.php" rel="nofollow">http://www.php.net/manual/en/types.comparisons.php</a></li>
</ol>

blocks|key|411847|text|您的函数返回false，所以我将使用该检查：if+($value+!=+false)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|411848|entityMap^0|6|5|M|K|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Your function returns <code>false</code>, so I would go with that check: <code>if ($value != false)</code>

blocks|key|1838283|text|$var3+=+"abc";
return+$var3;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1838284|那是毫无意义的。您是在return值，而不是变量。return+"abc";是非常好的。|unstyled|offset|length|style|CODE|1838285|1838286|可以返回值还是返回false？|blockquote|1838287|1838288|1838289|是的，对于这样一个简单的案例来说，这是非常好的。|1838290|1838291|如何检查函数是否返回了$var3？|1838292|1838293|1838294|如上所述，函数返回的是值"abc"，而不是$var3。您将它保存在一个新的变量$value中。这个变量是明确设置的(您刚刚在那里创建了它)，所以不需要isset或empty。只需测试它的值是true还是false+(或者其他您想要测试的东西)。所以你做得很好。|1838295|entityMap^0|0|B|6|P|D|0|0|0|0|0|0|0|0|0|0|C|5|L|5|13|6|23|5|29|5|2N|4|2T|5|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|12|8|@$G|13|H|14|I|J]|$G|15|H|16|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|17|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|18|8|@]|9|@]|A|$]]|$1|O|3|-4|5|F|7|19|8|@]|9|@]|A|$]]|$1|P|3|-4|5|F|7|1A|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|1B|8|@]|9|@]|A|$]]|$1|S|3|-4|5|F|7|1C|8|@]|9|@]|A|$]]|$1|T|3|U|5|N|7|1D|8|@]|9|@]|A|$]]|$1|V|3|-4|5|F|7|1E|8|@]|9|@]|A|$]]|$1|W|3|-4|5|F|7|1F|8|@]|9|@]|A|$]]|$1|X|3|Y|5|F|7|1G|8|@$G|1H|H|1I|I|J]|$G|1J|H|1K|I|J]|$G|1L|H|1M|I|J]|$G|1N|H|1O|I|J]|$G|1P|H|1Q|I|J]|$G|1R|H|1S|I|J]|$G|1T|H|1U|I|J]]|9|@]|A|$]]|$1|Z|3|-4|5|F|7|1V|8|@]|9|@]|A|$]]]|10|$]]

<pre><code>$var3 = "abc";
return $var3;
</code></pre>

That's pointless. You're <code>return</code>ing a value, not a variable. <code>return "abc";</code> is perfectly fine.

<blockquote>
 Is it ok to either return a value or return false?
</blockquote>

Yes, that's perfectly fine for a simple case such as this.

<blockquote>
 How can i check the function did return the $var3?
</blockquote>

As said above, the function returns the value <code>"abc"</code>, not <code>$var3</code>. You're saving it in a new variable <code>$value</code>. This variable is definitely set (you just created it right there), so there's no need for <code>isset</code> or <code>empty</code>. Just test whether its value is <code>true</code> or <code>false</code> (or whatever else you want to test for). So the way you're doing it in fine.

blocks|key|1858213|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1858214|是的，您可以从函数返回几乎任何东西，也可以“返回”而不返回任何内容。在您的示例中，您将得到一个字符串或"false“作为回报。要检查是否为false，请执行if+(！|ordered-list-item|1858215|)或if+($variable===false)。如果您执行"if+($variable==false)“，则零将返回true，这是由于自动将零转换为false+(以及任何其他正数变为true)。三个"===“确保它真的是假的，没有别的。isset($var)检查是否存在，而不是值，并且不适用于您的示例，因为您的函数将返回值或"false“，因此始终存在。|1858216|entityMap^0|0|0|0^^$0|@$1|2|3|-4|4|5|6|H|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|I|7|@]|8|@]|9|$]]|$1|D|3|E|4|5|6|J|7|@]|8|@]|9|$]]|$1|F|3|-4|4|5|6|K|7|@]|8|@]|9|$]]]|G|$]]

<ol>
<li>Yes, you can return pretty much anything from the function, or you can just "return" without returning anything. In your example, you'll get a string or "false" in return. </li>
<li>To check for false you either do if (!$variable) or if ($variable===false). Zero will return true if you do "if ($variable==false)" due to auto casting of zero to false (and any other positive number to true). Three "===" makes sure it really is false and nothing else. The isset($var) checks for existance, not value - and is not applicable to your example since your function will return a value or "false" and thus always exists.</li>
</ol>

blocks|key|411902|text|这里唯一正确的答案是:视情况而定。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|411903|在创建这样的函数时，我总是问自己这个问题。为了回答这个问题，我分析了函数的功能，而不是它返回的内容。|411904|例如，如果我有一个getter，我希望得到一个值，或者什么也得不到。在这种情况下，当什么都没有发现/出了什么问题时，我经常返回null。在我看来，像您这样的测试函数在任何时候都应该返回一个布尔值。我认为，在检查是否为true或false时返回变量在语义上是不正确的。|offset|length|style|CODE|411905|除了语义:返回0之外，在用if+(test($var1,+$var2))检查它时，false或null并不重要，因为所有这些操作都是一样的。但是，如果需要更详细的细节，则需要进行身份检查(===)，而不是进行等式检查。在PHP中，有时会出现这种情况，例如，strpos可以返回0或false，0是匹配的，而false则不是。因此，下列情况将失败：|411906|//+returns+0,+which+is+casted+to+false,+so+the+'else'+part+is+executed
if+(strpos('a',+'abc'))+{+
++++//+'abc'+contains+'a'
}+else+{
++++//+'abc'+does+not+contain+'a'
}|code-block|syntax|javascript|411907|长话短说:这取决于..。|411908|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.strpos.php^0|0|0|1R|4|0|D|N|2M|3|3K|6|3K|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|12|8|@$F|13|G|14|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|15|8|@$F|16|G|17|H|I]|$F|18|G|19|H|I]|$F|1A|G|1B|H|I]]|9|@$F|1C|G|1D|1|1E]]|A|$]]|$1|L|3|M|5|N|7|1F|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1G|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

The only right answer here is: it depends.

I always ask myself this question when creating a function like this. To answer it, I analyze what the function does, instead of what it returns. 

For instance, if I have a getter, I expect to get a value, or nothing. In this case I often return <code>null</code> when nothing is found/something went wrong. 
A test function like yours should return a boolean at all times, in my opinion. Returning a variable when you're checking for something to be true or false is semantically incorrect, I think.

Aside from the semantics: returning 0, false or null does not really matter when you're checking it with <code>if (test($var1, $var2))</code>, since it will all work the same. However, if you want some finer details, you want to do an identity check (<code>===</code>) rather than a equality check. In PHP this is sometimes the case, for instance <a href="http://php.net/manual/en/function.strpos.php" rel="nofollow"><code>strpos</code></a> can return 0 or false, 0 being a match is found, and false is not. Therefore the following would fail:

<pre><code>// returns 0, which is casted to false, so the 'else' part is executed
if (strpos('a', 'abc')) { 
 // 'abc' contains 'a'
} else {
 // 'abc' does not contain 'a'
}
</code></pre>

So, long story short: it depends...

I have very basic question regarding return value of a function, and checking the variable value.

<pre><code>function test($var1, $var2){
 if ($var1 == $var2){
 $var3 = "abc";
 return $var3;
 }
 return false
}

$value = test($var1, $var2);

if ($value){
 echo "Value is".$value; //should output abc.
} else {
 echo "Not equal";
}
</code></pre>

<ol>
<li>Is it ok to either return a value or return false? For example I am not returning TRUE, it is ok?</li>
<li>When i call the function, i store the return value in a variable $value. How can i check the function did return the $var3? Which of the if condition should be used?
<code>if (!empty($value))</code> or <code>if (isset($value))</code> or <code>if ($value)</code> or <code>if (value != false)</code></li>
</ol>

Is it correct way to return value 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。

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关于函数的返回值和检查变量值，我有一个非常基本的问题。function test($var1, $var2){    if ($var1 == $var2){            $var3 = "abc";            return $var3;        }    return false}$value = test($var1, $var2);if ($value){    

问在PHP中返回值正确吗？
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