PHP recursion, static variables, anonymous function use-PHP Tutorial-php.cn

PHP recursion, static variables, anonymous function use

巴扎黑

Release： 2023-03-03 12:50:02

Original

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<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>Current To-Do List</title>
</head>
<body>
<?php
    function make_list($parent) {
        global $tasks;
        echo &#39;<ol>&#39;;
        foreach($parent as $task_id => $todo) {
            echo "<li>$todo";
            if (isset($tasks[$task_id])) { // 如果当前id有子任务则递归创建菜单
                make_list($tasks[$task_id]);
            }
            echo "</li>";
        }
        echo &#39;</ol>&#39;;
    }
    $db = mysqli_connect(&#39;192.168.31.172&#39; ,&#39;root&#39;, &#39;root&#39;, &#39;phpadvanced&#39;);
    mysqli_query($db, "set names utf8");
    $q = &#39;SELECT task_id, parent_id, task FROM tasks WHERE date_completed="0000-00-00 00:00:00" 
    ORDER BY parent_id, date_added ASC&#39;;
    $r = mysqli_query($db, $q);
    $tasks = array();
while (list($task_id, $parent_id, $task) = mysqli_fetch_array($r, MYSQLI_NUM)) {
    $tasks[$parent_id][$task_id] = $task;
}
//echo &#39;<pre class="brush:php;toolbar:false">&#39;.print_r($tasks,1).&#39;

'; make_list($tasks[0]); //把包含顶级任务的数组发送给它, 最顶级的parent_id是0 ?>

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Static variable statistics code

<?php
// create the array.
// Array structs
// StudentId = > ["name" => "Name", "grade" => xx.x];
$students = [
    256 => [&#39;name&#39; => &#39;Jon&#39;, &#39;grade&#39; => &#39;98.5&#39;],
    2 => [&#39;name&#39; => &#39;Vance&#39;, &#39;grade&#39; => &#39;85.1&#39;],
    9 => [&#39;name&#39; => &#39;Stephen&#39;, &#39;grade&#39; => &#39;94.0&#39;],
    364 => [&#39;name&#39; => &#39;Steve&#39;, &#39;grade&#39; => &#39;85.1&#39;],
    68 => [&#39;name&#39; => &#39;Rob&#39;, &#39;grade&#39; => &#39;74.6&#39;],
];
function name_sort($x, $y) {
    static $count = 1;
    echo "<p>Iteration $count: {$x[&#39;name&#39;]} vs. {$y[&#39;name&#39;]} </p>\n";
    $count ++;
    return strcasecmp($x[&#39;name&#39;], $y[&#39;name&#39;]);
}
function grade_sort($x, $y) {
    static $count = 1;
    echo "<p>Iteration $count: {$x[&#39;grade&#39;]} vs. {$y[&#39;grade&#39;]}</p>\n";
    $count++;
    return $x[&#39;grade&#39;] < $y[&#39;grade&#39;];
}
echo print_r($students, 1);
uasort($students, &#39;name_sort&#39;); //保持键并使用自定义排序
echo print_r($students, 1);
uasort($students, &#39;grade_sort&#39;);
echo print_r($students, 1);
?>

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Anonymous function - closure code

<?php
// create the array.
// Array structs
// StudentId = > ["name" => "Name", "grade" => xx.x];
$students = [
    256 => [&#39;name&#39; => &#39;Jon&#39;, &#39;grade&#39; => &#39;98.5&#39;],
    2 => [&#39;name&#39; => &#39;Vance&#39;, &#39;grade&#39; => &#39;85.1&#39;],
    9 => [&#39;name&#39; => &#39;Stephen&#39;, &#39;grade&#39; => &#39;94.0&#39;],
    364 => [&#39;name&#39; => &#39;Steve&#39;, &#39;grade&#39; => &#39;85.1&#39;],
    68 => [&#39;name&#39; => &#39;Rob&#39;, &#39;grade&#39; => &#39;74.6&#39;],
];
echo print_r($students, 1);
uasort($students, function($x, $y){
    return strcasecmp($x[&#39;name&#39;], $y[&#39;name&#39;]);
}); //保持键并使用自定义排序
echo print_r($students, 1);
uasort($students, function($x, $y){
    return $x[&#39;grade&#39;] < $y[&#39;grade&#39;];
});
echo print_r($students, 1);
?>

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Passing parameters by reference, used when the data is a big data, there is no need to copy a copy of the data code

<?php
function increment(&$i) {
    $i++;
}
$num = 2;
increment($num);
echo $num;
?>

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