What function does php use to reverse arrays?

In PHP, you can use the array_reverse() function to reverse the array. The array_reverse() function will reverse the order of the elements in the array, create a new array and return it. The syntax is "array_reverse(array,preserve)"; the parameter preserve can be omitted and is used to specify whether to retain the key names of the original array (only for numbers) Key name, non-numeric keys are not affected).

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

In PHP, you can use array_reverse () function to implement array reversal.

array_reverse() function returns an array in the reverse order of elements; it reverses the order of elements in the original array, creates a new array, and returns it.

Grammar format:

array_reverse(array,preserve)

Parameters	Description
array	Required. Specifies an array.
preserve	Optional. Specifies whether to retain the original array key names. If set to TRUE, numeric keys will be preserved. Non-numeric keys are not affected by this setting and will always be retained. Possible values: true false

##Example:

<?php
header("Content-type:text/html;charset=utf-8");
$array= array("香蕉","苹果","梨子","橙子","橘子","榴莲");

var_dump(array_reverse($array));
var_dump(array_reverse($array,true));
?>

Original array:

Reversed array:

• The preserve parameter can be omitted , used to specify whether to retain the key names of the original array (only for numeric key names, non-numeric keys are not affected).

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
$arr =array("a"=>"Volvo","b"=>"BMW","c"=>"Toyota");
echo "原数组顺序：";
var_dump($arr);
echo "<br>数组反转后的顺序：";
var_dump(array_reverse($arr));
var_dump(array_reverse($arr,true));
?>

Extended knowledge: Use the for loop statement to reverse the index array

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
$array= array("香蕉","苹果","梨子","橙子","橘子","榴莲");
echo "原数组顺序：";
var_dump($array);
for ($i=count($array)-1; $i>=0 ; $i--) { 
    $res[]=$array[$i];
} 
echo "数组反转后的顺序：";
var_dump($res);
?>

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