blocks|key|1100642|text|$array+=+array(+'one'+=>'value',+'two'+=>+'value2'+);

$allKeys+=+array_keys($array);
echo+$allKeys[0];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1100643|它将输出：|unstyled|1100644|one|1100645|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>$array = array( 'one' =&gt;'value', 'two' =&gt; 'value2' );

$allKeys = array_keys($array);
echo $allKeys[0];
</code></pre>

Which will output:

<pre><code>one
</code></pre>

blocks|key|1100652|text|或者如果您需要在循环中使用它|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1100653|foreach+($array+as+$key+=>+$value)
{
++++echo+$key+.+':'+.+$value+.+"\n";
}
//Result:+
//one:value
//two:value2|code-block|syntax|javascript|1100654|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|$]]

Or if you need it in a loop

<pre><code>foreach ($array as $key =&gt; $value)
{
 echo $key . ':' . $value . "\n";
}
//Result: 
//one:value
//two:value2
</code></pre>

blocks|key|1100667|text|$array+=+array(+'one'+=>'value',+'two'+=>+'value2'+);
$keys++=+array_keys($array);
echo+$keys[0];+//+one
echo+$keys[1];+//+two|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1100668|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>$array = array( 'one' =&gt;'value', 'two' =&gt; 'value2' );
$keys = array_keys($array);
echo $keys[0]; // one
echo $keys[1]; // two
</code></pre>

blocks|key|885875|text|你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|885876|function+asoccArrayValueWithNumKey(&$arr,+$key)+{
+++if+(!(count($arr)+>+$key))+return+false;
+++reset($array);
+++$aux+++=+-1;
+++$found+=+false;
+++while+(($auxKey+=+key($array))+&&+!$found)+{
++++++$aux%2B%2B;
++++++$found+=+($aux+==+$key);
+++}
+++if+($found)+return+$array[$auxKey];
+++else+return+false;
}

$val+=+asoccArrayValueWithNumKey($array,+0);
$val+=+asoccArrayValueWithNumKey($array,+1);
etc...|code-block|syntax|javascript|885877|我没有尝试过代码，但我很确定它会工作的。|885878|祝好运!|885879|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You might do it this way:

<pre><code>function asoccArrayValueWithNumKey(&amp;$arr, $key) {
 if (!(count($arr) &gt; $key)) return false;
 reset($array);
 $aux = -1;
 $found = false;
 while (($auxKey = key($array)) &amp;&amp; !$found) {
 $aux++;
 $found = ($aux == $key);
 }
 if ($found) return $array[$auxKey];
 else return false;
}

$val = asoccArrayValueWithNumKey($array, 0);
$val = asoccArrayValueWithNumKey($array, 1);
etc...
</code></pre>

Haven't tryed the code, but i'm pretty sure it will work.

Good luck!

blocks|key|885927|text|如果您只打算使用一个特定的键，那么只需一行代码即可完成此操作，而不必存储所有键的数组：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|885928|echo+array_keys($array)[$i];|code-block|syntax|javascript|885929|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 you only plan to work with one key in particular, you may accomplish this with a single line without having to store an array for all of the keys:

<pre><code>echo array_keys($array)[$i];
</code></pre>

blocks|key|1100772|text|根据Ram+Dane的回答，key函数是获取数组当前索引的键的另一种方法。您可以创建以下函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1100773|++++function+get_key($array,+$index){
++++++$idx=0;
++++++while($idx!=$index++&&+next($array))+$idx%2B%2B;
++++++if($idx==$index)+return+key($array);
++++++else+return+'';
++++}|code-block|syntax|javascript|1100774|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.key.php^0|E|3|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]]]]

Expanding on Ram Dane's answer, the <a href="http://php.net/manual/en/function.key.php" rel="nofollow">key</a> function is an alternative way to get the key of the current index of the array. You can create the following function,

<pre><code> function get_key($array, $index){
 $idx=0;
 while($idx!=$index &amp;&amp; next($array)) $idx++;
 if($idx==$index) return key($array);
 else return '';
 }
</code></pre>

blocks|key|1100804|text|如果是第一个元素，即$array[0]，您可以尝试：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1100805|echo+key($array);|code-block|syntax|javascript|1100806|如果是第二个元素，即$array[1]，您可以尝试：|1100807|next($array);
echo+key($array);|1100808|我认为当需要的元素是数组的第一个、第二个或至多第三个元素时，应该使用此方法。对于其他情况，应该使用循环，否则代码的可读性会降低。|1100809|entityMap^0|A|9|0|0|A|9|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

If it is the first element, i.e. <code>$array[0]</code>, you can try: 

<pre><code>echo key($array);
</code></pre>

If it is the second element, i.e. <code>$array[1]</code>, you can try: 

<pre><code>next($array);
echo key($array);
</code></pre>

I think this method is should be used when required element is the first, second or at most third element of the array. For other cases, loops should be used otherwise code readability decreases.

blocks|key|886042|text|再举一个例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|886043|获取数组中最频繁出现的项：|886044|PHP+>=+7.3：|886045|$+php+--version
PHP+7.4.3+(cli)+(built:+Oct++6+2020+15:47:56)+(+NTS+)
Copyright+(c)+The+PHP+Group
Zend+Engine+v3.4.0,+Copyright+(c)+Zend+Technologies
++++with+Zend+OPcache+v7.4.3,+Copyright+(c),+by+Zend+Technologies

$+php+-a
Interactive+mode+enabled

php+>+$a+=+array_count_values(array('abc','abc','def','def','def'));
php+>+var_dump($a);
array(2)+{
++["abc"]=>
++int(2)
++["def"]=>
++int(3)
}
php+>+arsort($a);
php+>+var_dump($a);
array(2)+{
++["def"]=>
++int(3)
++["abc"]=>
++int(2)
}
php+>+var_dump(array_key_first($a));
string(3)+"def"
php+>+var_dump(array_keys($a)[1]);
string(3)+"abc"|code-block|syntax|javascript|886046|如果您有密钥，就可以很容易地查询值(=频率)。|886047|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|R|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

One more example:
Get the most frequent occurrence(s) in an array:
PHP &gt;= 7.3:
<pre><code>$ php --version
PHP 7.4.3 (cli) (built: Oct 6 2020 15:47:56) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
 with Zend OPcache v7.4.3, Copyright (c), by Zend Technologies

$ php -a
Interactive mode enabled

php &gt; $a = array_count_values(array('abc','abc','def','def','def'));
php &gt; var_dump($a);
array(2) {
 [&quot;abc&quot;]=&gt;
 int(2)
 [&quot;def&quot;]=&gt;
 int(3)
}
php &gt; arsort($a);
php &gt; var_dump($a);
array(2) {
 [&quot;def&quot;]=&gt;
 int(3)
 [&quot;abc&quot;]=&gt;
 int(2)
}
php &gt; var_dump(array_key_first($a));
string(3) &quot;def&quot;
php &gt; var_dump(array_keys($a)[1]);
string(3) &quot;abc&quot;
</code></pre>
If you have the key, you can easily query the value (= the frequency).

blocks|key|886079|text|我只是为那些array_keys()不起作用的人发布了另一个解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|886080|$myAssociativeArray+=+[
++'name'+=>+'sun',
++'age'+=>+21
);

$arrayKeys+=+[];
foreach($myAssociativeArray+as+$key+=>+$val){
++++array_push($arrayKeys,+$key);
}

print_r($arrayKeys)

//+['name',+'age']|code-block|syntax|javascript|886081|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|$]]

just posting another solution for those that array_keys() is not working
<pre><code>$myAssociativeArray = [
 'name' =&gt; 'sun',
 'age' =&gt; 21
);

$arrayKeys = [];
foreach($myAssociativeArray as $key =&gt; $val){
 array_push($arrayKeys, $key);
}

print_r($arrayKeys)

// ['name', 'age']
</code></pre>

If I have:

<pre><code>$array = array( 'one' =&gt;'value', 'two' =&gt; 'value2' );
</code></pre>

how do I get the string <code>one</code> back from <code>$array[1]</code> ?

php: how to get associative array key from numeric index?

如果我有：$array = array( 'one' =>'value', 'two' => 'value2' );如何从$array[1]取回字符串one？

问php:如何从数字索引中获取关联数组键？
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