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Hàm arsort() trong PHP

Hướng dẫn cách sử dụng hàm arsort() về mảng trong lập trình PHP

Tác dụng của hàm arsort()

The arsort() function sorts an associative array in descending order, according to the value.

The keys are preserved, i.e. the key-to-value mapping will remain unchanged by the sort operation.

The following table summarizes the technical details of this function.

Return Value: Returns TRUE on success or FALSE on failure.
Version: PHP 4+

Syntax

The basic syntax of the arsort() function is given with:

arsort(array, sort_flags);

The following example shows the arsort() function in action.

<?php
// Sample array
$alphabets = array("b"=>"ball", "d"=>"dog", "a"=>"apple", "c"=>"cat");

// Sorting alphabets array
arsort($alphabets);
print_r($alphabets);
?>

Tip: The arsort() and asort() functions mainly used for sorting associative arrays by value, whereas krsort() and ksort() functions used for sorting associative arrays by key.


Parameters

The arsort() function accepts the following parameters.

Parameter Description
array Required. Specifies the array to sort.
sort_flags

Optional. Specifies how array items should be compared. Possible values are:

  • SORT_REGULAR – Compare items normally (don't change types). Default value.
  • SORT_NUMERIC – Compare items numerically.
  • SORT_STRING – Compare items as strings.
  • SORT_LOCALE_STRING – Compare items as strings, based on the current locale.
  • SORT_NATURAL – Compare items as strings using natural ordering.
  • SORT_FLAG_CASE – Can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively.

More Examples

Here're some more examples showing how arsort() function actually works:

The following example sorts an associative array having numeric values in descending order:

<?php
// Sample array
$persons = array("Harry"=>18, "Clark"=>32, "Peter"=>20, "John"=>24);

// Sorting persons array
arsort($persons);
print_r($persons);
?>

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