arsort

说明

bool arsort ( array &array [, int sort_flags] )

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。

如果成功则返回 TRUE，失败则返回 FALSE。

例子 1. arsort() 例子


<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
foreach ($fruits as $key => $val) {
    echo "$key = $val\n";
}
?>

上例将输出：

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

fruits 被按照字母顺序逆向排序，并且单元的索引关系不变。

可以用可选的参数 sort_flags 改变排序的行为，详情见 sort()。

参见 asort()，rsort()，ksort() 和 sort()。

add a note User Contributed Notes

Scott Woods
03-Feb-2005 12:21


Note about "morgan at anomalyinc dot com"'s comment:



As of PHP4, you can just use array_multisort() to sort parallel or multi-dimensional arrays.

rodders_plonker at yahoo dot com
22-Aug-2000 09:43


I was having trouble with the arsort() function on an older version of PHP which was returning an error along the lines of 'wrong perameter count for function arsort' when I tried to use a flag for numeric sorting (2/SORT_NUMERIC).


I figured, as I only wanted to sort integers, I could pad numbers from the left to a specific length with 0's (using the lpad function provided by improv@magma.ca in the notes at http://www.php.net/manual/ref.strings.php).


A string sort then correctly sorts numerically (i.e. {30,2,10,21} becomes {030,021,010,002} not {30,21,2,10}) when echoing the number an (int)$string_name hides the leading 0's.





Made my day :).





Rodders.

morgan at anomalyinc dot com
25-Nov-1999 11:30


If you need to sort a multi-demension array, for example, an array such as 





$TeamInfo[$TeamID]["WinRecord"] 


$TeamInfo[$TeamID]["LossRecord"] 


$TeamInfo[$TeamID]["TieRecord"] 


$TeamInfo[$TeamID]["GoalDiff"]


$TeamInfo[$TeamID]["TeamPoints"] 





and you have say, 100 teams here, and want to sort by "TeamPoints":





first, create your multi-dimensional array. Now, create another, single dimension array populated with the scores from the first array, and with indexes of corresponding team_id... ie


$foo[25] = 14


$foo[47] = 42


or whatever.


Now, asort or arsort the second array.


Since the array is now sorted by score or wins/losses or whatever you put in it, the indices are all hoopajooped.


If you just walk through the array, grabbing the index of each entry, (look at the asort example. that for loop does just that) then the index you get will point right back to one of the values of the multi-dimensional array.


Not sure if that's clear, but mail me if it isn't...


-mo

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