How to ascend a two-dimensional array in php

Learn PHP development in depth, and there are many common problems that need to be solved. Something as basic as sorting a two-dimensional array in ascending order. In this article, we will explore how to sort a 2D array in ascending order in PHP.

A two-dimensional array is a type of PHP array that contains an ordered set of values. It has more dimensions than a one-dimensional array and can be nested within other arrays. This makes 2D arrays ideal for processing large amounts of data.

In PHP, we can sort an array using the sort function, which sorts the array according to the ASCII code table in ascending order, and the opposite in descending order. For one-dimensional arrays, it is easy to sort using the sort function, but for two-dimensional arrays, additional processing is required.

To sort a two-dimensional array, we need to specify a "key" to sort each sub-array. A key is an attribute in an array that is used for comparison and sorting. In this case, the "key" can be any attribute of the array, such as name, date, price, or ID, etc.

A simple way is to use the PHP function array_column() that searches for a specific key name in a two-dimensional array. This function returns an array containing all values ​​for the specified key. Select the key we want to sort from, and we can use the array_multisort() function to sort the key in ascending order.

The following is a sample code for operating an array, which uses array_column() and array_multisort() to sort a two-dimensional array in ascending order.

<?php
$employees = array(
  array('name' => 'John Smith', 'age' => 28, 'salary' => 3000),
  array('name' => 'Anna Black', 'age' => 33, 'salary' => 2500),
  array('name' => 'Peter Brown', 'age' => 24, 'salary' => 2200),
  array('name' => 'Emma Rose', 'age' => 29, 'salary' => 3500),
);

// 排序前的数组
echo "排序前：<br>";
print_r($employees);

// 获取所有员工的工资
$salary = array_column($employees, 'salary');

// 按升序排序员工工资
array_multisort($salary, SORT_ASC, $employees);

// 排序后的数组
echo "排序后：<br>";
print_r($employees);
?>

In the above sample code, we first define a two-dimensional array containing data such as employee name, age and salary. We use the print_r() function to display the results before sorting. Next, we use the array_column() function to get the salary values ​​of all employees and store them in a variable. Finally, we use the array_multisort() function to sort this variable in ascending order and sort the original array using the same order. We use the print_r() function again to display the sorted results.

This sample code will output the following results:

排序前：
Array
(
    [0] => Array
        (
            [name] => John Smith
            [age] => 28
            [salary] => 3000
        )

    [1] => Array
        (
            [name] => Anna Black
            [age] => 33
            [salary] => 2500
        )

    [2] => Array
        (
            [name] => Peter Brown
            [age] => 24
            [salary] => 2200
        )

    [3] => Array
        (
            [name] => Emma Rose
            [age] => 29
            [salary] => 3500
        )

)

排序后：
Array
(
    [0] => Array
        (
            [name] => Peter Brown
            [age] => 24
            [salary] => 2200
        )

    [1] => Array
        (
            [name] => Anna Black
            [age] => 33
            [salary] => 2500
        )

    [2] => Array
        (
            [name] => John Smith
            [age] => 28
            [salary] => 3000
        )

    [3] => Array
        (
            [name] => Emma Rose
            [age] => 29
            [salary] => 3500
        )

)

As shown above, through the cooperation of array_column() and array_multisort() functions, we can easily sort the two-dimensional array in ascending order.

For other types of sorting, simply change the first parameter of the array_multisort() function to use a different attribute.

In PHP, there are many interesting functions and methods that can simplify our workload. Mastering this knowledge will help you process large amounts of data more efficiently, thereby improving your PHP development capabilities.

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