How to reverse an array in php

In PHP, we can sort the array in reverse order by using the array_reverse() function. Next let us explain in detail how to use and apply this function.

1. array_reverse() function

array_reverse() function is a function used in PHP to arrange array elements in reverse order. Its syntax is as follows:

array array_reverse ( array $array [, bool $preserve_keys = FALSE ] )

It receives two parameters, the first parameter is the array to be sorted in reverse order, and the second parameter is a Boolean value, which determines whether to retain the key name. The default is false, which means the key name is not retained. If the value is true, key names will be preserved.

2. Using the array_reverse() function

Next we will demonstrate how to use the array_reverse() function to sort an array in reverse order.

Sample code:

$fruits = array("apple", "banana", "orange", "lemon", "peach");
$reversed_fruits = array_reverse($fruits);

print_r($reversed_fruits);

Output:

Array
(
    [0] => peach
    [1] => lemon
    [2] => orange
    [3] => banana
    [4] => apple
)

In this example, we can see that the order of the elements in the original $fruits array is apple, banana, orange ,lemon,peach. And when we use this array as the input parameter of the array_reverse() function, we get a new array $reversed_fruits, whose element order is reversed.

3. Keep the key name

We can modify the above example code and set the second parameter to true to keep the key name. The code is as follows:

Sample code:

$fruits = array("a" => "apple", "b" => "banana", "o" => "orange", "l" => "lemon", "p" => "peach");
$reversed_fruits = array_reverse($fruits, true);

print_r($reversed_fruits);

Output:

Array
(
    [p] => peach
    [l] => lemon
    [o] => orange
    [b] => banana
    [a] => apple
)

In this example, the key names of the original array $fruits are "a", "b" , "o", "l", "p", and when we use this array as the input parameter of the array_reverse() function, we get a new array $reversed_fruits, which still retains the original key names and sorts the elements in order. Arranged in reverse order.

4. Summary

By using the array_reverse() function, we can quickly reverse the order of the elements of an array. We can also choose whether to preserve key names.

In actual development, we can use this function to sort the data to facilitate our operation and display of the data.

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