你如何在 PHP 中重新索引一个数组？
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How do you reindex an array in PHP?
提问by meleyal
I have the following array, which I would like to reindex so the keys are reversed (ideally starting at 1):
我有以下数组，我想对其重新索引，以便将键反转（理想情况下从 1 开始）：
Current array (edit:the array actually looks like this):
当前数组（编辑：数组实际上是这样的）：
Array (
[2] => Object
(
[title] => Section
[linked] => 1
)
[1] => Object
(
[title] => Sub-Section
[linked] => 1
)
[0] => Object
(
[title] => Sub-Sub-Section
[linked] =>
)
)
How it should be:
应该如何：
Array (
[1] => Object
(
[title] => Section
[linked] => 1
)
[2] => Object
(
[title] => Sub-Section
[linked] => 1
)
[3] => Object
(
[title] => Sub-Sub-Section
[linked] =>
)
)
回答by Andrew Moore
If you want to re-index starting to zero, simply do the following:
如果要重新索引从零开始，只需执行以下操作：
$iZero = array_values($arr);
If you need it to start at one, then use the following:
如果您需要从一个开始，请使用以下命令：
$iOne = array_combine(range(1, count($arr)), array_values($arr));
Here are the manual pages for the functions used:
以下是所用函数的手册页：
回答by Sandra
Here is the best way:
这是最好的方法：
# Array
$array = array('tomato', '', 'apple', 'melon', 'cherry', '', '', 'banana');
that returns
返回
Array
(
[0] => tomato
[1] =>
[2] => apple
[3] => melon
[4] => cherry
[5] =>
[6] =>
[7] => banana
)
by doing this
通过做这个
$array = array_values(array_filter($array));
you get this
你得到这个
Array
(
[0] => tomato
[1] => apple
[2] => melon
[3] => cherry
[4] => banana
)
Explanation
解释
array_values(): Returns the values of the input array and indexes numerically.
array_values()：以数字形式返回输入数组和索引的值。
array_filter(): Filters the elements of an array with a user-defined function (UDF If none is provided, all entries in the input table valued FALSE will be deleted.)
array_filter()：使用用户定义的函数过滤数组的元素（UDF如果没有提供，则输入表中所有值为 FALSE 的条目将被删除。）
回答by imagiro
I just found out you can also do a
我刚刚发现你也可以做一个
array_splice($ar, 0, 0);
That does the re-indexing inplace, so you don't end up with a copy of the original array.
这会进行重新索引，因此您最终不会得到原始数组的副本。
回答by Gumbo
Why reindexing? Just add 1 to the index:
为什么要重新索引？只需将 1 添加到索引：
foreach ($array as $key => $val) {
echo $key + 1, '<br>';
}
Edit???After the question has been clarified: You could use the array_valuesto reset the index starting at 0. Then you could use the algorithm above if you just want printed elements to start at 1.
编辑???在问题得到澄清后：您可以使用array_values来重置从 0 开始的索引。然后，如果您只想打印元素从 1 开始，则可以使用上面的算法。
回答by Peter Bailey
Well, I would like to think that for whatever your end goal is, you wouldn't actually need to modify the array to be 1-based as opposed to 0-based, but could instead handle it at iteration time like Gumbo posted.
好吧，我想无论您的最终目标是什么，您实际上都不需要将数组修改为基于 1 而不是基于 0，而是可以像 Gumbo 发布的那样在迭代时处理它。
However, to answer your question, this function should convert any array into a 1-based version
但是，要回答您的问题，此函数应将任何数组转换为基于 1 的版本
function convertToOneBased( $arr )
{
return array_combine( range( 1, count( $arr ) ), array_values( $arr ) );
}
EDIT
编辑
Here's a more reusable/flexible function, should you desire it
这是一个更可重用/灵活的功能，如果您需要的话
$arr = array( 'a', 'b', 'c' );
echo '<pre>';
print_r( reIndexArray( $arr ) );
print_r( reIndexArray( $arr, 1 ) );
print_r( reIndexArray( $arr, 2 ) );
print_r( reIndexArray( $arr, 10 ) );
print_r( reIndexArray( $arr, -10 ) );
echo '</pre>';
function reIndexArray( $arr, $startAt=0 )
{
return ( 0 == $startAt )
? array_values( $arr )
: array_combine( range( $startAt, count( $arr ) + ( $startAt - 1 ) ), array_values( $arr ) );
}
回答by Greg
This will do what you want:
这将执行您想要的操作：
<?php
$array = array(2 => 'a', 1 => 'b', 0 => 'c');
array_unshift($array, false); // Add to the start of the array
$array = array_values($array); // Re-number
// Remove the first index so we start at 1
$array = array_slice($array, 1, count($array), true);
print_r($array); // Array ( [1] => a [2] => b [3] => c )
?>
回答by Michael Trausch
You may want to consider why you want to use a 1-based array at all. Zero-based arrays (when using non-associative arrays) are pretty standard, and if you're wanting to output to a UI, most would handle the solution by just increasing the integer upon output to the UI.
您可能需要考虑为什么要使用基于 1 的数组。从零开始的数组（当使用非关联数组时）是非常标准的，如果你想输出到 UI，大多数人会通过在输出到 UI 时增加整数来处理解决方案。
Think about consistency—both in your application and in the code you work with—when thinking about 1-based indexers for arrays.
在考虑数组的基于 1 的索引器时，请考虑一致性——无论是在您的应用程序中还是在您使用的代码中。
回答by Nigel Alderton
You can reindex an array so the new array starts with an index of 1 like this;
你可以重新索引一个数组，这样新数组的索引从 1 开始，就像这样；
$arr = array(
'2' => 'red',
'1' => 'green',
'0' => 'blue',
);
$arr1 = array_values($arr); // Reindex the array starting from 0.
array_unshift($arr1, ''); // Prepend a dummy element to the start of the array.
unset($arr1[0]); // Kill the dummy element.
print_r($arr);
print_r($arr1);
The output from the above is;
上面的输出是;
Array
(
[2] => red
[1] => green
[0] => blue
)
Array
(
[1] => red
[2] => green
[3] => blue
)
回答by Ionu? Ple?ca
A more elegant solution:
更优雅的解决方案：
$list = array_combine(range(1, count($list)), array_values($list));
回答by Nick
Similar to @monowerker, I needed to reindex an array using an object's key...
与@monowerker 类似，我需要使用对象的键重新索引数组...
$new = array();
$old = array(
(object)array('id' => 123),
(object)array('id' => 456),
(object)array('id' => 789),
);
print_r($old);
array_walk($old, function($item, $key, &$reindexed_array) {
$reindexed_array[$item->id] = $item;
}, &$new);
print_r($new);
This resulted in:
这导致：
Array
(
[0] => stdClass Object
(
[id] => 123
)
[1] => stdClass Object
(
[id] => 456
)
[2] => stdClass Object
(
[id] => 789
)
)
Array
(
[123] => stdClass Object
(
[id] => 123
)
[456] => stdClass Object
(
[id] => 456
)
[789] => stdClass Object
(
[id] => 789
)
)
