asort()

(PHP 4, PHP 5, PHP 7)

对数组进行排序并保持索引关系

说明

本函数对数组进行排序，数组的索引保持和单元的关联。主要用于对那些单元顺序很重要的结合数组进行排序。

If two members compare as equal, their relative order in the sorted array is undefined.

参数

输入的数组。

可以用可选的参数$sort_flags改变排序的行为，详情见sort()。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

Example #1asort()例子

以上例程会输出：

c = apple
b = banana
d = lemon
a = orange

fruits 被按照字母顺序排序，并且单元的索引关系不变。

参见

• arsort() 对数组进行逆向排序并保持索引关系
• 数组排序函数对比

This function can be used to sort multidimensional arrays with almost no work whatsoever by using the individual values within the custom sort function.
This function passes the entire child element even if it is not a string. If it is an array, as would be the case in multidimensional arrays, it will pass the whole child array as one parameter.
Therefore, do something elegant like this:

This does in 4 lines what other functions took 40 to 50 lines to do. This does not require you to create temporary arrays or anything. This is, for me, a highly preferred solution.
Hope it helps!

For a recent project I needed to sort an associative array by value first, and then by key if a particular value appeared multiple times. I wrote this function to accomplish the task. Note that the parameters default to sort ascending on both keys and values, but allow granular control over each. 

This is a function to sort an indexed 2D array by a specified sub array key, either ascending or descending.
It is usefull for sorting query results from a database by a particular field after the query has been returned
This function can be quite greedy. It recreates the array as a hash to use ksort() then back again
By default it will sort ascending but if you specify $reverse as true it will return the records sorted descending 

Example Outputs:
Before: Array
(
  [0] => Array ( [code] => LHR, [name] => Heathrow )
  [1] => Array ( [code] => LGW, [name] => Gatwick )
)
After: Array
(
  [0] => Array ( [code] => LGW, [name] => Gatwick )
  [1] => Array ( [code] => LHR, [name] => Heathrow )
)

This is a fixed version of the same function I posted below. Now it will handle duplicate entries in the sorted field. EG: If there were two records that had the name Heathrow it would still work. 

Small typo in the aksort function I just submitted. Here's the entire thing again, with the correction noted: 

asort has one anoying feature, it ignores any default or implicit order in the data. i.e. if two elements of an array contain "banana" then it is not garanteed that the first will still be the first after the sort.
This makes the Burrows-Wheeler block sort a bit of a pain to impliment, with a trailing string having to be appended to all strings before sorting, and removed after sorting. To maintain the so called "banana" order.

acecream's function works fine, especially with the spectre extension.
nevertheless sometimes the index values have to be kept. To achieve this, just replace:
$sorted_arr[] = $array[$arr_key]; 
with:
$sorted_arr[$arr_key] = $array[$arr_key];

Advanced sort array by second index function, which produces ascending (default) or descending output and uses optionally natural case insensitive sorting (which can be optionally case sensitive as well).
Only the first two arguments are required. 

Ok I was mistaken, after re-reading the previous post the ".$key" is important. What caused the sorting issue for me wasn't that at all. But rather something else.
doing an: asort($records, $flags); before returning fixes the sorting problems.
The sorting problem I was refearing to causes a character based sorting done on numeric data.
so instead of:
1
2
3
...
10
12
20
It was returned back as
1
10
12
2
20
3
...
basically what I was trying to fix in the first place.

Here's my version of sorting multi-dimensional array by 2nd index.
Feel free to change the code to suit your needs. 

The asortbyindex($sortarray, $index) looks like sort not asort. The key of the $sortarray was changed.

Similar to above but for an array of arrays instead of an array of objects.

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