Can php arrays be sorted?

php arrays can be sorted. PHP has a variety of array sorting functions: 1. sort(), which can be sorted in ascending order, with the syntax "sort(array)"; 2. rsort(), which can be sorted in descending order, with the syntax "rsort(array)"; 3. shuffle( ), can be randomly sorted, the syntax is "shuffle(array)".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

php array can be sorted.

php provides a variety of built-in functions for different array sorting needs (key value, key name, ascending order, descending order, etc.).

1. Sort the array in ascending order

There are three commonly used array ascending order sorting functions in PHP:

• sort(): Sort the array elements in ascending order

• asort(): Sort the array in ascending order according to the key value of the associated array

• ksort(): Sort the array in ascending order according to the key name of the associated array

1. Use the sort() function

## The #sort() function sorts the array elements in ascending order (from small to large, from low to high).

<?php
header("Content-type:text/html;charset=utf-8");
$arr1 = array(10, 23, 5, 12, 84, 16);
sort($arr1);
var_dump($arr1);

$arr2= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
sort($arr2);
var_dump($arr2);
?>

Output:

sort() function has two parameters: $array (required) and $sortingtype (can be omitted ).

Among them, the $sortingtype parameter is used to define the function sorting mode and specify how to compare the elements/items of the array. The default value is "SORT_REGULAR".

The $sortingtype parameter can be set to the following values:

• 0 = SORT_REGULAR: Compare array elements normally without changing their type (default value);

• 1 = SORT_NUMERIC: Treat array elements as numbers;

##2 = SORT_STRING: Treat array elements as strings;
3 = SORT_LOCALE_STRING: Compare array elements as strings based on the current locale (can be changed via setlocale()).
4 = SORT_NATURAL: Similar to natsort(), it sorts strings in "natural order" for each array element. It is new in PHP5.4.0.
5 = SORT_FLAG_CASE: Can be combined with SORT_STRING or SORT_NATURAL (OR bitwise operation), case-insensitive sorting string.

<?php
header("Content-type:text/html;charset=utf-8");
$arr1 = array(10, 23, 5, 12, 84, 16);
sort($arr1,2);
var_dump($arr1);

$arr2= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
sort($arr2,1);
var_dump($arr2);
?>

Output result:

sort() function will not maintain the index relationship and will delete the array to the original key name and assign it a new numeric key name.

<?php
header("Content-type:text/html;charset=utf-8");
$age = array("张三"=>30,"李四"=>23,"王五"=>15,"李华"=>12,"娜娜"=>26,"小红"=>16);
sort($age);
var_dump($age);
?>

Output:

The sort() function can be used for arrays where the relationship between values ​​and indexes is not so important (numeric arrays), but Arrays that focus on the relationship between values ​​and indexes are not suitable. At this point, you need to use the asort() and ksort() functions.

2. Use the asort() function

The asort() function will sort the associative array in ascending order based on the key values ​​and will not modify the key names in the original array. .

header("Content-type:text/html;charset=utf-8");
$age = array("张三"=>30,"李四"=>23,"王五"=>15,"李华"=>12,"娜娜"=>26,"小红"=>16);
asort($age);
var_dump($age);
?>

Output:

asort() function also has two parameters, the parameter values ​​are the same as the sort() function, you can refer to.

3. Use the ksort() function

The ksort() function will sort the associated array in ascending order according to the key name, and will not modify the original array. key name.

<?php
header("Content-type:text/html;charset=utf-8");
$age = array("张三"=>30,"李四"=>23,"王五"=>15,"李华"=>12,"娜娜"=>26,"小红"=>16);
ksort($age);
var_dump($age);
?>

Output:

##

<?php
header("Content-type:text/html;charset=utf-8");
$arr= array("l"=>"lemon", "o"=>"orange", "b"=>"banana", "a"=>"apple");
ksort($arr);
var_dump($arr);
?>

Output:

## The #ksort() function also has two parameters. The parameter values ​​are the same as the sort() function. You can refer to them.

2. Sort the array in descending order

There are three commonly used array descending sort functions in PHP:

rsort(): Sort the array elements in descending order

• arsort(): Sort the array in descending order according to the key value of the associated array

• krsort(): Sort the array in descending order according to the key name of the associated array

• 1. Use the rsort() function

rsort() function is used to sort array elements in descending order, that is, from large to small and from high to low. Let’s take a look at the code example:

<?php
header("Content-type:text/html;charset=utf-8");
$arr = array(2, 1, 5, 16, 29, 15);
rsort($arr);
var_dump($arr);
?>

Output result:

rsort() 函数有两个参数：$array（必须）和$sortingtype（可省略）。$sortingtype参数用于表示排序模式，具体取值可以参考上篇文章的sort()函数。下文arsort()和krsort()同样参考sort()函数。

<?php
header("Content-type:text/html;charset=utf-8");
$arr = array(2, 1, 5, 16, 29, 15);
rsort($arr,2);
var_dump($arr);
?>

输出结果：

rsort()和sort()函数一样，都不会保持索引关系，会删除数组中原有的键名，并为其重新赋值；因此不适合用于注重值和索引间关系的数组。

2、使用arsort()函数

arsort()函数会根据关联数组的键值进行降序排序，且不会修改原数组中的键名。

<?php
header("Content-type:text/html;charset=utf-8");
$age = array("张三"=>30,"李四"=>23,"王五"=>15,"李华"=>12,"娜娜"=>26,"小红"=>16);
arsort($age);
var_dump($age);

arsort($age,2);
var_dump($age);
?>

输出结果：

3、使用krsort()函数

krsort()函数会根据关联数组的键名进行降序排序，也不会修改原数组中的键名。

<?php
header("Content-type:text/html;charset=utf-8");
$arr= array("l"=>"lemon", "o"=>"orange", "b"=>"banana", "a"=>"apple");
krsort($arr);
var_dump($arr);

krsort($arr,1);
var_dump($arr);
?>

输出结果：

3、随机排序

在PHP中，可以使用shuffle()函数随机排序，打乱数组元素。

shuffle()函数会把数组中的元素按随机顺序重新排列。

<?php
header("Content-type:text/html;charset=utf-8");
$arr1 = array(10, 23, 5, 12, 84, 16);
shuffle($arr1);
var_dump($arr1);

$arr2= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
shuffle($arr2);
var_dump($arr2);
?>

输出结果：

刷新一下，结果就改变了：

说明：shuffle()函数不仅会将数组随机打乱，还会删除数组中原有的键名，并为其赋与新的数值键名（即不会保持索引关系）。

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