array
Needed to get the index of the max/highest value in an assoc array.
max() only returned the value, no index, so I did this instead.
<?php
reset($x); // optional.
arsort($x);
$key_of_max = key($x); // returns the index.
?>
arsort
(PHP 4, PHP 5)
arsort — 배열을 내림차순 정렬하고 인덱스의 상관관계를 유지
설명
bool arsort
( array &$array
[, int $sort_flags
] )
이 함수는 배열 인덱스가 그 배열의 원소와 상관관계를 유지할수 있도록 배열을 정렬한다.
이 함수는 주로 실제 원소의 정렬이 중요한 연관 배열을 정렬할 때 이용한다.
반환값
성공할 경우 TRUE를, 실패할 경우 FALSE를 반환합니다.
예제
Example #1 arsort() 예제
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>
위 예제의 출력:
a = orange d = lemon b = banana c = apple
fruits는 알파벳 내림 차순으로 정렬되었고, 각 원소와 연관된 인덱스가 유지되었다.
add a note
User Contributed Notes
arsort
FatBat
13-Oct-2011 07:40
jordancdarwin at googlemail dot com
15-Dec-2007 07:21
A lot of people seem to trip up on this and ask me questions as to debugging. Bear in mind that this returns boolean, and does not return an array of affected items.
$array = array("One"=>1, "Three" => 3,"Two" =>2);
print_r(asort($array));
If successful, will return 1, and error if there is a string used. Useful to note so then people stop asking me :D
Scott Woods
02-Feb-2005 01:21
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
21-Aug-2000 12:43
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
24-Nov-1999 12:30
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