blocks|key|1716612|text|在PHP+7中，您现在可以使用null合并运算符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1716613|$var+??+$default|code-block|syntax|javascript|1716614|这与您的函数非常相似|1716615|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

From PHP 7, you can now use the null coalescing operator :

<pre class="lang-php prettyprint-override"><code>$var ?? $default
</code></pre>

that does exactly like your function

blocks|key|3051605|text|您可以在一个脚本中定义它，然后在其他脚本中require_once该脚本|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3051606|您也可以只使用三元运算符：|3051607|$myVar+=+isset($var)?$var:$default;|code-block|syntax|javascript|3051608|entityMap^0|L|C|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You can define it in one script and then <code>require_once</code> that script in your other scripts

You could also just use the ternary operator:

<pre><code>$myVar = isset($var)?$var:$default;
</code></pre>

blocks|key|1716368|text|使用这个简明的替代方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1716369|isset($myVar)+%7C%7C+$myvar=$default;|code-block|syntax|javascript|1716370|%7C%7C运算符是短路的，如果第一个运算符被评估为真，它将不会计算第二个运算符。|offset|length|style|CODE|1716371|entityMap^0|0|0|0|2|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Use this concise alternative:

<pre><code>isset($myVar) || $myvar=$default;
</code></pre>

The <code>||</code> operator is short circuit, it will not evaluate second operant if the first one be evaluated true.

blocks|key|1327888|text|使用更少的代码来做你需要的事情。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1327889|您不需要使用_?_:_格式再次指定该变量。|offset|length|style|CODE|1327890|echo+$var?:"default";|code-block|syntax|javascript|1327891|等同于|1327892|echo+$var?$var:"default";|1327893|现在就空检查而言，您可以使用@来静音通知，我不确定技术后果，但您已经在使用此格式时进行自己的检查：|1327894|echo+@$non_existing_var?:"default";|1327895|下面是一些例子：|1327896|<?php

++++$nope+=+null;
++++$yup+=+"hello";
++++echo+($nope?:$yup)+.+"\n"+;
++++echo+($yup?:$nope)++.+"\n"+;

++++$items+=+[+'one',+'two',+false,+'three',+'four',+null+];

++++foreach($items+as+$item):
++++++++echo($item?:"default+shown+(".var_export($item,true).")")."\n";
++++endforeach;

++++echo(@$non_existing?:"default+for+non-existant+variable!");

?>|1327897|输出：|1327898|$+php+variabledefault.php
+hello
+hello
+one
+two
+default+shown+(false)
+three
+four
+default+shown+(NULL)
+default+for+non-existant+variable!%25+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++|1327899|entityMap^0|0|6|5|0|0|0|0|E|1|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@$D|16|E|17|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|18|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1B|8|@$D|1C|E|1D|F|G]]|9|@]|A|$]]|$1|S|3|T|5|J|7|1E|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|1F|8|@]|9|@]|A|$]]|$1|W|3|X|5|J|7|1G|8|@]|9|@]|A|$K|L]]|$1|Y|3|Z|5|6|7|1H|8|@]|9|@]|A|$]]|$1|10|3|11|5|J|7|1I|8|@]|9|@]|A|$K|L]]|$1|12|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|13|$]]

Use less code to do what you need.

You don't need to specify the variable again using the <code>_?_:_</code> format.

<pre><code>echo $var?:"default";
</code></pre>

Is the same as

<pre><code>echo $var?$var:"default";
</code></pre>

Now as far as an empty check, you could use <code>@</code> to mute notices, I'm not sure of the technical ramifications, but you're already doing your own checking while using this format:

<pre><code>echo @$non_existing_var?:"default";
</code></pre>

Some examples:

<pre><code>&lt;?php

 $nope = null;
 $yup = "hello";
 echo ($nope?:$yup) . "\n" ;
 echo ($yup?:$nope) . "\n" ;

 $items = [ 'one', 'two', false, 'three', 'four', null ];

 foreach($items as $item):
 echo($item?:"default shown (".var_export($item,true).")")."\n";
 endforeach;

 echo(@$non_existing?:"default for non-existant variable!");

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

Output:

<pre><code>$ php variabledefault.php
 hello
 hello
 one
 two
 default shown (false)
 three
 four
 default shown (NULL)
 default for non-existant variable!% 
</code></pre>

blocks|key|3051663|text|在本例中，您可以使用我的小型库ValueResolver，例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3051664|$myVar+=+ValueResolver::resolve($var,+$default);|code-block|syntax|javascript|3051665|别忘了使用名称空间use+LapaLabs\ValueResolver\Resolver\ValueResolver;|style|CODE|3051666|还可以进行类型转换，例如，如果您的变量的值应该为integer，则使用以下命令：|3051667|$id+=+ValueResolver::toInteger('6+apples',+1);+//+returns+6
$id+=+ValueResolver::toInteger('There+are+no+apples',+1);+//+returns+1+(used+default+value)|3051668|有关更多示例，请查看docs|3051669|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/LapaLabs/ValueResolver|1^0|F|D|0|0|0|9|1E|0|O|7|0|0|A|4|1|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@$A|12|B|13|1|14]]|C|$]]|$1|D|3|E|5|F|7|15|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|16|8|@$A|17|B|18|K|L]]|9|@]|C|$]]|$1|M|3|N|5|6|7|19|8|@$A|1A|B|1B|K|L]]|9|@]|C|$]]|$1|O|3|P|5|F|7|1C|8|@]|9|@]|C|$G|H]]|$1|Q|3|R|5|6|7|1D|8|@]|9|@$A|1E|B|1F|1|1G]]|C|$]]|$1|S|3|-4|5|6|7|1H|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]|10|$5|V|W|X|C|$Y|Z]]]]

You could use my tiny library <a href="https://github.com/LapaLabs/ValueResolver" rel="nofollow">ValueResolver</a> in this case, for example:

<pre><code>$myVar = ValueResolver::resolve($var, $default);
</code></pre>

and don't forget to use namespace <code>use LapaLabs\ValueResolver\Resolver\ValueResolver;</code>

There are also ability to typecasting, for example if your variable's value should be <code>integer</code>, so use this:

<pre><code>$id = ValueResolver::toInteger('6 apples', 1); // returns 6
$id = ValueResolver::toInteger('There are no apples', 1); // returns 1 (used default value)
</code></pre>

Check the <a href="https://github.com/LapaLabs/ValueResolver" rel="nofollow">docs</a> for more examples

blocks|key|1716625|text|Null+coalescing+operator已经添加到PHP7.0版本中，它所做的就是替换|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1716626|$username+=+isset($_GET['user'])+?+$_GET['user']+:+'nobody';|code-block|syntax|javascript|1716627|使用较短的版本：|1716628|$username+=+$_GET['user']+??+'nobody';|1716629|上面的代码行做的是检查是否设置了$_GET['user']，并且不是null，然后将其赋给$username变量，如果没有设置$_GET['user']+(因此是null)，它将缺省为'nobody'字符串，因此$username为nobody。|style|CODE|1716630|您的代码应该如下所示：|1716631|echo+$foo+??+"bar\n";
$foobar+=+"foobar";
echo+$foobar+??+"ERROR";|1716632|entityMap|0|LINK|mutability|MUTABLE|url|https://www.php.net/manual/en/migration70.new-features.php#migration70.new-features.null-coalesce-op^0|0|O|0|0|0|0|0|G|D|19|9|1R|D|2K|8|2Y|9|38|6|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@$A|13|B|14|1|15]]|C|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|17|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|18|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|19|8|@$A|1A|B|1B|O|P]|$A|1C|B|1D|O|P]|$A|1E|B|1F|O|P]|$A|1G|B|1H|O|P]|$A|1I|B|1J|O|P]|$A|1K|B|1L|O|P]]|9|@]|C|$]]|$1|Q|3|R|5|6|7|1M|8|@]|9|@]|C|$]]|$1|S|3|T|5|F|7|1N|8|@]|9|@]|C|$G|H]]|$1|U|3|-4|5|6|7|1O|8|@]|9|@]|C|$]]]|V|$W|$5|X|Y|Z|C|$10|11]]]]

The <a href="https://www.php.net/manual/en/migration70.new-features.php#migration70.new-features.null-coalesce-op" rel="nofollow noreferrer">Null coalescing operator</a> has been added to PHP version 7.0, what it does is replaces
<pre class="lang-php prettyprint-override"><code>$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';
</code></pre>
with a shorter version:
<pre class="lang-php prettyprint-override"><code>$username = $_GET['user'] ?? 'nobody';
</code></pre>
What the line above does, is check if <code>$_GET['user']</code> is set, and not null, then it will assign that to the <code>$username</code> variable, if <code>$_GET['user']</code> is not set (and thus null) it will default to the <code>'nobody'</code> string so <code>$username</code> is <code>nobody</code>.
Your code should look like:
<pre class="lang-php prettyprint-override"><code>echo $foo ?? &quot;bar\n&quot;;
$foobar = &quot;foobar&quot;;
echo $foobar ?? &quot;ERROR&quot;;
</code></pre>

I want to get a value from the session, but use a default if it is not defined. And ofcourse I want to circumvent the PHP notice.
You can write a function that does this
<pre><code>function get(&amp;$var, $default){
 if(isset($var)) return $var;
 return $default;
}

echo get($foo, &quot;bar\n&quot;);
$foobar = &quot;foobar&quot;;
echo get($foobar, &quot;ERROR&quot;);
</code></pre>
<a href="http://codepad.org/FzTPuvBO" rel="nofollow noreferrer">Example in action</a>
Is there a way to do this without defining this function in every file?

PHP variable "default value"

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我想从会话中获取一个值，但如果没有定义，则使用默认值。当然，我想绕过PHP的通知。您可以编写一个函数来执行此操作function get(&$var, $default){    if(isset($var)) return $var;    return $default;}echo get($foo, "bar\n");$foobar = "foobar";echo get($foobar, 

问PHP变量"default value“
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