blocks|key|1209124|text|如果数组中有元素，reset()会给出数组的第一个值：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209125|$value+=+reset($array);|code-block|syntax|javascript|1209126|它还会在数组为空的情况下提供FALSE。|1209127|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.reset.php^0|9|7|9|7|0|0|0|E|5|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

<a href="http://php.net/manual/en/function.reset.php" rel="noreferrer"><code>reset()</code></a> gives you the first value of the array if you have an element inside the array:

<pre><code>$value = reset($array);
</code></pre>

It also gives you <code>FALSE</code> in case the array is empty.

blocks|key|1424080|text|有几个选择。array_shift()将返回第一个元素，但也会从数组中删除第一个元素。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1424081|$first+=+array_shift($array);|code-block|syntax|javascript|1424082|current()将返回其内部内存指针所指向的数组的值，这是默认情况下的第一个元素。|1424083|$first+=+current($array);|1424084|如果您希望确保它指向第一个元素，则可以始终使用reset()。|1424085|reset($array);
$first+=+current($array);|1424086|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/array_shift|1|http://php.net/current|2|http://php.net/reset^0|6|D|6|D|0|0|0|0|9|0|9|1|0|0|N|7|N|7|2|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@$9|17|A|18|1|19]]|E|$]]|$1|F|3|G|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@$9|1E|A|1F|1|1G]]|E|$]]|$1|M|3|N|5|H|7|1H|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@$9|1L|A|1M|1|1N]]|E|$]]|$1|Q|3|R|5|H|7|1O|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|1P|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]|10|$5|V|W|X|E|$Y|11]]|12|$5|V|W|X|E|$Y|13]]]]

There's a few options. <a href="http://php.net/array_shift" rel="noreferrer"><code>array_shift()</code></a> will return the first element, but it will also remove the first element from the array.

<pre><code>$first = array_shift($array);
</code></pre>

<a href="http://php.net/current" rel="noreferrer"><code>current()</code></a> will return the value of the array that its internal memory pointer is pointing to, which is the first element by default.

<pre><code>$first = current($array);
</code></pre>

If you want to make sure that it is pointing to the first element, you can always use <a href="http://php.net/reset" rel="noreferrer"><code>reset()</code></a>.

<pre><code>reset($array);
$first = current($array);
</code></pre>

blocks|key|1424102|text|您可以使用array_shift|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1424103|entityMap|0|LINK|mutability|MUTABLE|url|http://us2.php.net/manual/en/function.array-shift.php^0|5|B|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You could use <a href="http://us2.php.net/manual/en/function.array-shift.php" rel="nofollow noreferrer">array_shift</a>

blocks|key|1209321|text|我们可以做$first+=+reset($array);|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209322|而不是|1209323|reset($array);
$first+=+current($array);|code-block|syntax|javascript|1209324|作为reset()|1209325|返回重置后数组的第一个元素；|1209326|entityMap^0|5|N|0|0|0|2|7|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

We can do 
<code>$first = reset($array);</code>

Instead of 

<pre><code>reset($array);
$first = current($array);
</code></pre>

As <code>reset()</code> 

returns the first element of the array after reset;

blocks|key|1424291|text|在获取第一个元素之前，测试a变量是否为数组。当动态创建数组时，如果将其设置为null，则会得到一个错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1424292|例如：|1424293|if(is_array($array))
{
++reset($array);
++$first+=+key($array);
}|code-block|syntax|javascript|1424294|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Test if the a variable is an array before getting the first element. When dynamically creating the array if it is set to null you get an error.

For Example:

<pre><code>if(is_array($array))
{
 reset($array);
 $first = key($array);
}
</code></pre>

blocks|key|1209475|text|只是为了让我们有一些其他的选择:如果你不想保持数组指针的位置，那么reset($arr);就足够好了，并且对于非常大的数组，它产生的开销最小。也就是说，它存在一些问题：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209476|$arr+=+array(1,2);
current($arr);+//+1
next($arr);++++//+2
current($arr);+//+2
reset($arr);+++//+1
current($arr);+//+1+!This+was+2+before!+We've+changed+the+array's+pointer.|code-block|syntax|javascript|1209477|在不更改指针的情况下执行此操作的方法：|1209478|$arr[reset(array_keys($arr))];+//+OR
reset(array_values($arr));|1209479|$arr[reset(array_keys($arr))];的好处是，如果数组实际上是空的，它会发出警告。|1209480|entityMap^0|X|C|0|0|0|0|0|U|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]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

Just so that we have some other options: <code>reset($arr);</code> good enough if you're not trying to keep the array pointer in place, and with very large arrays it incurs an minimal amount of overhead. That said, there are some problems with it:

<pre><code>$arr = array(1,2);
current($arr); // 1
next($arr); // 2
current($arr); // 2
reset($arr); // 1
current($arr); // 1 !This was 2 before! We've changed the array's pointer.
</code></pre>

The way to do this without changing the pointer:

<pre><code>$arr[reset(array_keys($arr))]; // OR
reset(array_values($arr));
</code></pre>

The benefit of <code>$arr[reset(array_keys($arr))];</code> is that it raises an warning if the array is actually empty.

blocks|key|1209503|text|我这样做是为了得到第一个和最后一个值。这也适用于更多的值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209504|$a+=+array(
++++'foo'+=>+400,
++++'bar'+=>+'xyz',
);
$first+=+current($a);+++//400
$last+=+end($a);++++//xyz|code-block|syntax|javascript|1209505|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|$]]

I do this to get the first and last value. This works with more values too. 

<pre><code>$a = array(
 'foo' =&gt; 400,
 'bar' =&gt; 'xyz',
);
$first = current($a); //400
$last = end($a); //xyz
</code></pre>

blocks|key|1209554|text|另一种简单易用的方法是使用array_values|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209555|array_values($array)[0]|code-block|syntax|javascript|1209556|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|$]]

another easy and simple way to do it use array_values 

<pre><code>array_values($array)[0]
</code></pre>

blocks|key|1424486|text|你可以试试这个。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1424487|要获取数组的第一个值:-|1424488|<?php
+++$large_array+=+array('foo'+=>+'bar',+'hello'+=>+'world');
+++var_dump(current($large_array));
?>|code-block|syntax|javascript|1424489|获取数组的第一个键|1424490|<?php
+++$large_array+=+array('foo'+=>+'bar',+'hello'+=>+'world');
+++$large_array_keys+=+array_keys($large_array);
+++var_dump(array_shift($large_array_keys));
?>|1424491|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can try this.

To get first value of the array :-

<pre><code>&lt;?php
 $large_array = array('foo' =&gt; 'bar', 'hello' =&gt; 'world');
 var_dump(current($large_array));
?&gt;
</code></pre>

To get the first key of the array 

<pre><code>&lt;?php
 $large_array = array('foo' =&gt; 'bar', 'hello' =&gt; 'world');
 $large_array_keys = array_keys($large_array);
 var_dump(array_shift($large_array_keys));
?&gt;
</code></pre>

blocks|key|1424519|text|您可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1424520|$values+=+array_values($array);
echo+$values[0];|code-block|syntax|javascript|1424521|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|$]]

You can make:

<pre><code>$values = array_values($array);
echo $values[0];
</code></pre>

blocks|key|1209660|text|使用reset()函数从该数组中获取第一项，而不需要知道它的键，如下所示。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209661|​|1209662|$value+=+array('foo'+=>+400,+'bar'+=>+'xyz');
echo+reset($value);|code-block|syntax|javascript|1209663|1209664|输出//+400|1209665|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|P|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|R|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|M|$]]

Use reset() function to get the first item out of that array without knowing the key for it like this.

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-html lang-html prettyprint-override"><code>$value = array('foo' =&gt; 400, 'bar' =&gt; 'xyz');
echo reset($value);</code></pre>
</div>
</div>


output //
400

blocks|key|1209698|text|从PHP+7.3.0开始，可以不重置内部指针。您将使用array_key_first。如果你确定你的数组中有值，那么你可以这样做：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1209699|$first+=+$array[array_key_first($array)];|code-block|syntax|javascript|1209700|更有可能的是，您需要处理数组为空的情况：|1209701|$first+=+(empty($array))+?+$default+:+$array[array_key_first($array)];|1209702|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.array-key-first.php^0|R|F|1|9|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

Starting with <a href="http://php.net/manual/en/function.array-key-first.php" rel="nofollow noreferrer">PHP 7.3.0</a> it's possible to do without resetting the internal pointer. You would use <code>array_key_first</code>. If you're sure that your array has values it in then you can just do:

<pre><code>$first = $array[array_key_first($array)];
</code></pre>

More likely, you'll want to handle the case where the array is empty:

<pre><code>$first = (empty($array)) ? $default : $array[array_key_first($array)];
</code></pre>

blocks|key|1424640|text|您可以只使用$array[0]。它将始终为您提供第一项|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1424641|entityMap^0|6|9|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

you can just use <code>$array[0]</code>. it will give you the first item always

blocks|key|1209813|text|在一行代码中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209814|$array['foo']+=+400;
$array['bar']+=+'xyz';
echo+'First+value=+'+.+$array[array_keys($array)[0]];|code-block|syntax|javascript|1209815|扩展：|1209816|$keys+=+array_keys($array);
$key+=+$keys[0];
$value+=+$array[$key];
echo+'First+value+=+'+.+$value;|1209817|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]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

In one line:
<pre><code>$array['foo'] = 400;
$array['bar'] = 'xyz';
echo 'First value= ' . $array[array_keys($array)[0]];
</code></pre>
Expanded:
<pre><code>$keys = array_keys($array);
$key = $keys[0];
$value = $array[$key];
echo 'First value = ' . $value;
</code></pre>

blocks|key|1209835|text|您可以使用array_values|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1209836|$firstValue+=+array_values($array)[0];|code-block|syntax|javascript|1209837|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|$]]

You could use array_values
<pre><code>$firstValue = array_values($array)[0];
</code></pre>

If I had an array like:

<pre><code>$array['foo'] = 400;
$array['bar'] = 'xyz';
</code></pre>

And I wanted to get the first item out of that array without knowing the key for it, how would I do that? Is there a function for this?

How to get the first item from an associative PHP array?

如果我有一个这样的数组：$array['foo'] = 400;$array['bar'] = 'xyz';我想在不知道它的键的情况下从数组中获取第一项，我该怎么做呢？有没有这样的函数呢？

问如何从关联PHP数组中获取第一项？
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问如何从关联PHP数组中获取第一项？
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