PHP implements unlimited classification, PHP implements level classification_PHP tutorial

php realizes unlimited classification, php realizes level classification

Copy code The code is as follows:

$area = array(
array('id'=>1,'name'=>'Anhui','parent'=>0),
array('id'=>2,'name'=>'Haidian','parent'=>7),
array('id'=>3,'name'=>'Suixi County','parent'=>5),
array('id'=>4,'name'=>'Changping','parent'=>7),
array('id'=>5,'name'=>'Huaibei','parent'=>1),
array('id'=>6,'name'=>'Chaoyang','parent'=>7),
array('id'=>7,'name'=>'Beijing','parent'=>0),
array('id'=>8,'name'=>'Shangdi','parent'=>2)
);

1. Recursion, search descendant tree

Copy code The code is as follows:

function subtree($arr,$id=0,$lev=1) {
$subs = array(); // Array of descendants
foreach($arr as $v) {
If($v['parent'] == $id) {
               $v['lev'] = $lev;
                  $subs[] = $v; // For example, find array('id'=>1,'name'=>'Anhui','parent'=>0),
                $subs = array_merge($subs,subtree($arr,$v['id'],$lev+1));
}
}
Return $subs;
}
$tree = subtree($area,0,1);
foreach($tree as $v) {
echo str_repeat(' ',$v['lev']),$v['name'],'
';
}

2. Recursion, find the family tree

Family tree applications, such as breadcrumb navigation Home page > Mobile phone type > CDMA mobile phone > Public Welfare PHP > Recursive application

Copy code The code is as follows:

function familytree($arr,$id) {
$tree = array();
foreach($arr as $v) {
           if($v['id'] == $id) {// Determine whether to find the parent column
If($v['parent'] > 0) { // parnet>0, it means there is a parent column
                    $tree = array_merge($tree,familytree($arr,$v['parent']));
            }
              $tree[] = $v; // Take finding Shangdi as an example
}
}
Return $tree;
}
print_r(familytree($area,8)); // Beijing->Haidian->Shangdi

2. Iterate and find the family tree

Copy code The code is as follows:

// Iteration is more efficient than recursion and does not require much code.
// Use iteration to find family tree recommendations
function tree($arr,$id) {
$tree = array();
While($id !== 0) {
         foreach($arr as $v) {
If($v['id'] == $id) {
                   $tree[] = $v;
                    $id = $v['parent'];
                 break;
                                                                       }
}
Return $tree;
}
print_r(tree($area,8));

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