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php多维数组排序以及实际工作中的应用

php  /  管理员 发布于 2020-03-08 13:33:15   26

自定义排序函数返回false或负数意味着第一个参数应该排在第二个参数的前面, 正数或true反之, 0相等

usort不保存键名

uasort 键名会保存下来

uksort 排序是对键名进行的

<!doctype html><html lang="en"><head>    <meta charset="utf-8">    <title>Sorting Multidimensional Arrays</title></head><body><?php$a = [    [        'key1' => 940,        'key2' => 'blah',    ],    [        'key1' => 23,        'key2' => 'this',    ],    [        'key1' => 894,        'key2' => 'that',    ],];var_dump($a);// 比较的规则第一个小于第二个返回负数或false, 相当于第一个的值减去第二个, 如果前小后大则为负, 前大后小则为正, 两个一样, 则为0//按第一个数组key1的数字从小到大排序function asc_number_sort($x, $y) {    echo "iteration x1 = ".$x['key1'].' y = '.$y['key1'];    if ($x['key1'] > $y['key1']) {        return true; // true或正数表示第二个参数应该排在前面, 小的在前    } elseif ($x['key1'] < $y['key1']) {        return false; // false或负数意味着第一个参数排第二个参数的前面, 小的在前    } else {        return 0; //表示两个数相等    }}usort($a, 'asc_number_sort');echo '针对key1从小到大排序';var_dump($a);//对第二个关键字进行排序function string_sort($x, $y) {    return strcasecmp($x['key2'], $y['key2']); // strcmp区分大小写 strcasecmp不区分大小写}usort($a, 'string_sort');echo '针对key2按字母排序';var_dump($a);// create the array.    // Array structs    // StudentId = > ["name" => "Name", "grade" => xx.x];    $students = [        256 => ['name' => 'Jon', 'grade' => '98.5'],        2 => ['name' => 'Vance', 'grade' => '85.1'],        9 => ['name' => 'Stephen', 'grade' => '94.0'],        364 => ['name' => 'Steve', 'grade' => '85.1'],        68 => ['name' => 'Rob', 'grade' => '74.6'],    ];    function name_sort($x, $y) {        return strcasecmp($x['name'], $y['name']);    }    function grade_sort($x, $y) {        return $x['grade'] < $y['grade'];    }echo print_r($students, 1);uasort($students, 'name_sort'); //保持键并使用自定义排序echo print_r($students, 1);uasort($students, 'grade_sort');echo print_r($students, 1);?></body></html>

 

<!doctype html><html lang="en"><head>    <meta charset="utf-8">    <title>Sorting Multidimensional Arrays</title></head><body><?php$db = mysqli_connect('192.168.31.172', 'root', 'root', 'phpadvanced');mysqli_query($db, "set names utf8");if(!empty($_POST['task'])) {    $parent_id = 0;    if(isset($_POST['parent_id']) && filter_var($_POST['parent_id'], FILTER_VALIDATE_INT, ['min_range' => 1])) {        $parent_id = $_POST['parent_id'];    }    $task = mysqli_real_escape_string($db, strip_tags($_POST['task']));    $q = "INSERT INTO tasks (parent_id, task) VALUES ($parent_id, '$task')";    echo $q;    $r = mysqli_query($db, $q);    if(mysqli_affected_rows($db) == 1) {        echo '<p>任务添加成功</p>';    } else {        echo '<p>任务添加失败</p>';    }}?>    <form action="add_task.php" method="post">        <fieldset>            <legend>添加一个任务</legend>            <p>任务: <input name="task" type="text" size="60" maxlength="100" required> </p>            <p>上级任务: <select name="parent_id">                    <option value="0">无上级</option>                    <?php                    $q = 'SELECT task_id, parent_id, task FROM tasks WHERE date_completed="0000-00-00 00:00:00" ORDER BY date_added ASC';                    $r = mysqli_query($db, $q);                    $tasks = [];                    while(list($task_id, $parent_id, $task) = mysqli_fetch_array($r, MYSQLI_NUM)) {                        echo "<option value=\"$task_id\">$task</option>";                        $tasks[] = ['task_id' => $task_id, 'parent_id' => $parent_id, 'task' => $task];                    }                    ?>                </select></p>            <input name="submit" type="submit" value="添加这个任务" />        </fieldset>    </form><?php    // 对任务的父id进行排序    function parent_sort($x, $y) {        return ($x['parent_id'] > $y['parent_id']);    }    usort($tasks, 'parent_sort');    echo '<h2>当前的任务列表</h2><ul>';    foreach ($tasks as $task) {        echo "<li>{$task['task']}</li>\n";    }echo '</ul>';?></body></html>

 

CREATE TABLE tasks (  task_id INT UNSIGNED NOT NULL AUTO_INCREMENT,  parent_id INT UNSIGNED NOT NULL DEFAULT 0,  task VARCHAR(100) NOT NULL,  date_added TIMESTAMP NOT NULL,  date_completed TIMESTAMP,  PRIMARY KEY (task_id),  INDEX parent (parent_id),  INDEX added (date_added),  INDEX completed (date_completed));

 


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