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PHP recursion, static variables, anonymous function use

巴扎黑

Nov 10, 2016 pm 02:04 PM

php static variable

Recursively read task list code

<!doctype html>  
<html lang="en">  
<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;

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'; make_list($tasks[0]); //Send it the array containing the top tasks, the top parent_id is 0 ?>

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 the copy of the data code

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

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