从 PHP 中的关联数组中弹出键和值
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Popping the key & value from an associative array in PHP
提问by Pietro Speroni
Let S be an associative array in PHP, I need to retrieve and extract from it the first element, both the value and the key.
让 S 成为 PHP 中的关联数组，我需要从中检索并提取第一个元素，包括值和键。
I would use
我会用
value1=array_pop(S);
but it only gives me the value.
但它只给了我价值。
I can use
我可以用
K=array_keys(S);
key1=array_pop(K);
value1=array_pop(S);
but it is complicated because it requires to have two copies of the same data. WHich is a confusing since the array is itself an element in an array of arrays. There must be a more elegant way to just read the couple key/value while extracting it.
但它很复杂，因为它需要有两个相同数据的副本。这是令人困惑的，因为数组本身就是数组数组中的一个元素。必须有一种更优雅的方法来在提取时读取一对键/值。
回答by hakre
$value = reset($arr);
$key = key($arr);
(in that order)
（以该顺序）
See reset()PHP Manual,
key()PHP Manual.
请参阅reset()PHP 手册、
key()PHP 手册。
unset($arr[$key]); # in case you want to remove it.
However array_pop()PHP Manualis working with the last element:
然而，array_pop()PHP 手册正在处理最后一个元素：
$value = end($arr);
$key = key($arr);
unset($arr[$key]); # in case you want to remove it.
See end()PHP Manual.
请参阅end()PHP 手册。
For the fun:
为了好玩：
list($value, $key) = array(end($arr), key($arr));
or
或者
extract(array('value'=>end($arr), 'key'=>key($arr)));
or
或者
end($arr);
list($key, $value) = each($arr);
or whatever style of play you like ;)
或任何你喜欢的游戏风格；)
Dealing with empty arrays
处理空数组
It was missing so far to deal with empty arrays. So it's a need to check if there is a last (first) element and if not, set the $keyto null(as nullcan not be an array key):
到目前为止还没有处理空数组。因此，需要检查是否有最后一个（第一个）元素，如果没有，则将其设置$key为null（因为null不能是数组键）：
for($key=null;$key===null&&false!==$value=end($arr);)
unset($arr[$key=key($arr)]);
This will give for a filled array like $arr = array('first' => '1st', 'last' => '2nd.');:
这将提供一个填充数组，如$arr = array('first' => '1st', 'last' => '2nd.');：
string(4) "2nd." # value
string(4) "last" # key
array(1) { # leftover array
["first"]=>
string(3) "1st"
}
And an empty array:
和一个空数组：
bool(false) # value
NULL # key
array(0) { # leftover array
}
Afraid of using unset?
害怕使用unset？
In case you don't trust unset()having the performance you need (of which I don't think it's really an issue, albeit I haven't run any metrics), you can use the native array_pop()implementation as well (but I really think that unset()as a language construct might be even faster):
如果您不相信unset()拥有所需的性能（我认为这不是问题，尽管我没有运行任何指标），您也可以使用本机array_pop()实现（但我真的认为这unset()是语言结构可能更快）：
end($arr);
$key = key($arr);
$value = array_pop($arr);
回答by OZ_
$arr = array('k1' => 'v1', 'k2' => 'v2', 'k3' => 'v3');
$a = array_slice($arr, 0, 1);
var_dump($a);
$arr = array_slice($arr, 1);
var_dump($arr);
array(1) {
["k1"]=>
string(2) "v1"
}
array(2) {
["k2"]=>
string(2) "v2"
["k3"]=>
string(2) "v3"
}
回答by Sander Marechal
$value = reset($array);
$key = key($array);
Edit: Hakre just beat me to it :-)
编辑：Hakre 击败了我 :-)
回答by KingCrunch
list($value, $key) = array(reset($s), key($s));
array_shift($s); // or just unset($s[$key]);
Of course you can split the first statement into two separate.
当然，您可以将第一个语句拆分为两个单独的语句。
