blocks|key|2511977|text|第一个示例创建该值的副本，而第二个示例使用对原始值的引用。因此，在第一个foreach运行之后，原始数组仍然保持不变。在第二个foreach之后，原始数组可能已经被修改，因为它是通过引用处理的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2511978|一些原生PHP函数已经以这种方式工作了，比如shuffle()，它会重新排列数组的内容。你会注意到这个函数并没有返回一个数组，你只需要调用它：|2511979|$myArray+=+array('foo',+'bar',+'fizz',+'buzz');
shuffle(+$myArray+);
//+$myArray+is+now+shuffled|code-block|syntax|javascript|2511980|它发挥了它的魔力，因为它通过引用来处理数组，而不是创建数组的副本。|2511981|还有一些函数不通过引用传递任何东西，而是处理原始值的副本，例如ucwords()，它返回新的结果字符串：|2511982|$myString+=+"hello+world";
$myString+=+ucwords(+$myString+);
//+$myString+is+now+capitalized|2511983|参见Passing+by+Reference。|2511984|entityMap|0|LINK|mutability|MUTABLE|url|http://us2.php.net/manual/en/function.shuffle.php|1|http://us2.php.net/manual/en/function.ucwords.php|2|http://www.php.net/manual/en/language.references.pass.php^0|10|7|1R|7|0|M|9|M|9|0|0|0|0|V|9|V|9|1|0|0|2|K|2|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@$9|1E|A|1F|1|1G]]|E|$]]|$1|H|3|I|5|J|7|1H|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1I|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1J|8|@$9|1K|A|1L|B|C]]|D|@$9|1M|A|1N|1|1O]]|E|$]]|$1|Q|3|R|5|J|7|1P|8|@]|D|@]|E|$K|L]]|$1|S|3|T|5|6|7|1Q|8|@]|D|@$9|1R|A|1S|1|1T]]|E|$]]|$1|U|3|-4|5|6|7|1U|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]|14|$5|X|Y|Z|E|$10|15]]]]

The first example creates a copy of the value, whereas the second uses a reference to the original value. So after the first <code>foreach</code> runs, the original array is still untouched. After the second <code>foreach</code> the original array could have been modified since it was handled by reference.

Some native PHP functions already work this way, such as <a href="http://us2.php.net/manual/en/function.shuffle.php" rel="noreferrer"><code>shuffle()</code></a> which rearranges the contents of your array. You'll notice that this function doesn't return an array, you just call it:

<pre><code>$myArray = array('foo', 'bar', 'fizz', 'buzz');
shuffle( $myArray );
// $myArray is now shuffled
</code></pre>

And it works its magic since it works with the array by reference rather than creating a copy of it.

Then there are functions that don't pass anything by reference but rather deal with a copy of the original value, such as <a href="http://us2.php.net/manual/en/function.ucwords.php" rel="noreferrer"><code>ucwords()</code></a> which returns the new resulting string:

<pre><code>$myString = "hello world";
$myString = ucwords( $myString );
// $myString is now capitalized
</code></pre>

See <a href="http://www.php.net/manual/en/language.references.pass.php" rel="noreferrer">Passing by Reference</a>.

blocks|key|4108305|text|Jonathan's+answers对此进行了很好的描述。为了完整起见，下面是您的两个示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4108306|4108307|只读取值：|ordered-list-item|4108308|4108309|$my_array+=+range(0,3)；foreach+($my_array+as+$my_value)+{+echo+$my_value+.PHP_EOL；}|4108310|将一些数字添加到每个元素(从而修改每个值)：|unordered-list-item|4108311|4108312|foreach+($my_array+as+&$my_value)+{+$my_value+%2B=+42；}|4108313|如果您不使用&$my_value，那么添加操作将不会对$my_array产生任何影响。但您也可以不使用引用来编写相同的代码：|style|CODE|4108314|foreach($my_array+as+$key=>$value)+{+$my_array$key+=+$value+%2B+42；}|4108315|不同之处在于，我们直接使用$my_array[$key].访问/更改原始值|4108316|4108317|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/4555263/php-whats-the-difference-between-var-and-var/4555273#4555273^0|0|I|0|0|0|0|0|0|0|0|0|6|A|R|9|0|0|D|F|0|0^^$0|@$1|2|3|4|5|6|7|17|8|@]|9|@$A|18|B|19|1|1A]]|C|$]]|$1|D|3|-4|5|6|7|1B|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|1C|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]|$1|I|3|J|5|6|7|1E|8|@]|9|@]|C|$]]|$1|K|3|L|5|M|7|1F|8|@]|9|@]|C|$]]|$1|N|3|-4|5|6|7|1G|8|@]|9|@]|C|$]]|$1|O|3|P|5|6|7|1H|8|@]|9|@]|C|$]]|$1|Q|3|R|5|6|7|1I|8|@$A|1J|B|1K|S|T]|$A|1L|B|1M|S|T]]|9|@]|C|$]]|$1|U|3|V|5|6|7|1N|8|@]|9|@]|C|$]]|$1|W|3|X|5|6|7|1O|8|@$A|1P|B|1Q|S|T]]|9|@]|C|$]]|$1|Y|3|-4|5|6|7|1R|8|@]|9|@]|C|$]]|$1|Z|3|-4|5|6|7|1S|8|@]|9|@]|C|$]]]|10|$11|$5|12|13|14|C|$15|16]]]]

<a href="https://stackoverflow.com/questions/4555263/php-whats-the-difference-between-var-and-var/4555273#4555273">Jonathan's answers</a> describes it very well. Just for completeness, here are your two examples:

<ol>
<li>Just reading values:

<pre><code>$my_array = range(0,3);
foreach ($my_array as $my_value) {
 echo $my_value . PHP_EOL;
}
</code></pre></li>
<li>Adding some number to each element (thus modifying each value):

<pre><code>foreach ($my_array as &amp;$my_value) {
 $my_value += 42;
}
</code></pre>

If you don't use <code>&amp;$my_value</code>, then the addition won't have any effect on <code>$my_array</code>.
But you could write the same not using references:

<pre><code>foreach($my_array as $key=&gt;$value) {
 $my_array[$key] = $value + 42;
}
</code></pre>

The difference is that we are accessing/changing the original value directly with <code>$my_array[$key]</code>.</li>
</ol>

<a href="http://codepad.org/n1AragXb" rel="nofollow noreferrer">DEMO</a>

blocks|key|1573521|text|当你在一个变量前面加上一个&符号时，你就是在创建一个“引用”。PHP引用就像计算机上的快捷方式或符号链接。您可以创建一个指针变量，它只是相同数据的另一个名称。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1573522|我看不出使用它们有什么很大的不同，除了你不会复制一个变量来节省内存。在传递变量时，可以只将引用和引用点传递给原始对象。|1573523|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|$]]

When you prefix a variable with an ampersand, you’re creating a “reference.” PHP references are like shortcuts or symlinks on your computer. You can create a pointer variable that is just another name for the same data.

I dont see a big difference in using these, except that you DONT COPY a variable saving memory. When you are passing variables you can just pass the reference and the reference points to the original object.

blocks|key|4108400|text|使用&的一个实际示例是，当您需要用很少的代码行来更改数组的内容时|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4108401|foreach($arrFeed+as+&$objFeed)
++$objFeed['externalSrc']+=+convertToLocalImage($objFeed['externalSrc']);|code-block|syntax|javascript|4108402|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|$]]

A real world example for &amp; use is when you need to change the content of an array with very few lines of code

<pre><code>foreach($arrFeed as &amp;$objFeed)
 $objFeed['externalSrc'] = convertToLocalImage($objFeed['externalSrc']);
</code></pre>

blocks|key|444982|text|只有当我必须读取csv文件才能知道分隔符是什么时，我才会使用引用。只需取第一行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|444983|$handle+=+fopen($file,+"r");
$firstLine+=+fgets($handle);
fclose($handle);|code-block|syntax|javascript|444984|然后使用这个可能的分隔符|444985|$delimiters+=+array(';'+=>+0,','+=>+0,"\t"+=>+0,"%7C"+=>+0);|444986|参考计数最常用的是什么|444987|foreach+($delimiters+as+$delimiter+=>+&$count)+{
++++$count+=+count(str_getcsv($firstLine,+$delimiter));
}
$delimiter+=++array_search(max($delimiters),+$delimiters);|444988|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I only use references when i have to read csv files to know what is the delimitier. Just take the first line:

<pre><code>$handle = fopen($file, "r");
$firstLine = fgets($handle);
fclose($handle);
</code></pre>

Then with this possible delimitiers

<pre><code>$delimiters = array(';' =&gt; 0,',' =&gt; 0,"\t" =&gt; 0,"|" =&gt; 0);
</code></pre>

Count by reference what is the most used

<pre><code>foreach ($delimiters as $delimiter =&gt; &amp;$count) {
 $count = count(str_getcsv($firstLine, $delimiter));
}
$delimiter = array_search(max($delimiters), $delimiters);
</code></pre>

What is the difference between

<pre><code>foreach ($my_array as $my_value) {
}
</code></pre>

And:

<pre><code>foreach ($my_array as &amp;$my_value) {
}
</code></pre>

?

May I ask you to give me two real-world examples of when to use one and when you use the other?

Php: what's the difference between $var and &$var?

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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它们之间的区别是什么foreach ($my_array as $my_value) {}和：foreach ($my_array as &$my_value) {}我可以请你给我两个真实世界的例子，告诉我什么时候使用一个，什么时候使用另一个？

问$var和&$var有什么区别？
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问$var和&$var有什么区别？EN