Sort array using sort() function in PHP

In PHP, array is a common data type, and arrays often need to be sorted in daily development work. PHP provides a built-in function sort() that can conveniently sort arrays. This article will introduce how to use the sort() function and sample applications.

1. The basic syntax and parameters of the sort() function

The syntax of the sort() function is as follows:

sort(array &$array[, int $sort_flags = SORT_REGULAR ]): bool

Among them, $array represents the array to be sorted, $sort_flags represents the sorting method, and the SORT_REGULAR method is used by default. $sort_flags can also use the following sorting methods:

1. SORT_REGULAR: Sort according to the normal comparison method (without changing the type)
2. SORT_NUMERIC: Sort according to the numerical comparison method
3. SORT_STRING : Sort according to string comparison method
4. SORT_LOCALE_STRING: Sort according to localized string comparison method
5. SORT_NATURAL: Sort strings in natural order (same as SORT_STRING), and are not case sensitive
6. SORT_FLAG_CASE: You can use SORT_STRING or SORT_NATURAL in combination, and it is not case-sensitive when comparing letters.

It should be noted here that the sort() function will directly modify the original array. , so you need to pass the array reference in the function parameter.

2. How to use the sort() function and its examples

The following introduces how to use the sort() function and its example applications.

1. Number array sorting example

First, we give an example of sorting a numeric array.

<?php
    $arr = array(3, 1, 5, 2, 4);
    sort($arr);
    print_r($arr);
?>

The output result is as follows:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

In the above example, we first define a numeric array $arr, which contains 5 elements. Next, we use the sort() function to sort the array, and then output the array in ascending order.

2. String array sorting example

Next, we give an example of sorting a string array.

<?php
    $arr = array("cat", "apple", "dog", "banana", "bird");
    sort($arr);
    print_r($arr);
?>

The output result is as follows:

Array
(
    [0] => apple
    [1] => banana
    [2] => bird
    [3] => cat
    [4] => dog
)

In the above example, we defined a string array $arr, which contains 5 elements, each element is a string. Then we use the sort() function to sort the array, and then output the array in lexicographic order.

3. Multidimensional array sorting example

Finally, we give a multidimensional array sorting example.

<?php
    $arr = array(
        array('id'=>1, 'name'=>'张三', 'age'=>30),
        array('id'=>2, 'name'=>'李四', 'age'=>25),
        array('id'=>3, 'name'=>'王五', 'age'=>28),
    );
    $sort = array_column($arr, 'age');
    array_multisort($sort , SORT_ASC, $arr);
    print_r($arr);
?>

The output results are as follows:

Array
(
    [0] => Array
        (
            [id] => 2
            [name] => 李四
            [age] => 25
        )
    [1] => Array
        (
            [id] => 3
            [name] => 王五
            [age] => 28
        )
    [2] => Array
        (
            [id] => 1
            [name] => 张三
            [age] => 30
        )
)

In the above example, we defined a multi-dimensional array $arr, which contains 3 elements, and each element is an associative array. We extract the 'age' field in each element through the array_column() function, then use the array_multisort() function to sort the array in ascending order of age, and output the sorted array.

3. Summary

This article introduces the basic syntax and parameters of the sort() function, and gives three examples of numeric arrays, string arrays, and multi-dimensional arrays. The sort() function is one of PHP's built-in sorting functions. It is simple and easy to use, and developers can apply it flexibly according to actual needs. In actual work, we often need to sort arrays, so it is important to master the use of the sort() function.

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