PHP无限分类
顶级分类下面有子分类，子分类下面又有孙分类，子子孙孙无穷尽也。
怎么让这个分类功能支持无限个，说是无限，其实也是有限。算法可以无限，实际使用中总是有限，毕竟计算机的内存是有限的。
无限分类实现如下：
function tree_list($list,$p_id = 0,$p_field='p_id'){
//用于保存整理好的分类节点
$tree = [];
// 循环所有分类
foreach ($list as $key => $value) {
// 如果当前分类的父id等于要寻找的父id则写入$tree 数组,并寻找当前分类id下的所有子分类
if($p_id == $value[$p_field]) {
$tree [$key] = $value;
$tree [$key] ['children'] = tree_list($list,$value ['id'],$p_field);
}
}
return $tree;
}
//假如这是数据库查出来的
$test_list=[
['id'=>1,'p_id'=>0,'name'=>'分类1'],
['id'=>2,'p_id'=>0,'name'=>'分类1'],//顶级分类
['id'=>3,'p_id'=>0,'name'=>'分类2'],//顶级分类
['id'=>4,'p_id'=>0,'name'=>'分类3'],//顶级分类
['id'=>5,'p_id'=>0,'name'=>'分类4'],//顶级分类
['id'=>6,'p_id'=>0,'name'=>'分类5'],//顶级分类
['id'=>7,'p_id'=>0,'name'=>'分类6'],//顶级分类
['id'=>8,'p_id'=>0,'name'=>'分类7'],//顶级分类
['id'=>9,'p_id'=>1,'name'=>'分类8（子）'],//子级分类
['id'=>10,'p_id'=>9,'name'=>'分类9（孙）'],//孙级分类
['id'=>11,'p_id'=>10,'name'=>'分类10（曾孙）'],//曾孙级分类
];
$tree_list=tree_list($test_list,$p_id = 0,$p_field='p_id');
print_r($tree_list);
输出：
Array
(
[0] => Array
(
[id] => 1
[p_id] => 0
[name] => 分类1
[children] => Array
(
[8] => Array
(
[id] => 9
[p_id] => 1
[name] => 分类8（子）
[children] => Array
(
[9] => Array
(
[id] => 10
[p_id] => 9
[name] => 分类9（孙）
[children] => Array
(
[10] => Array
(
[id] => 11
[p_id] => 10
[name] => 分类10（曾孙）
[children] => Array
(
)
)
)
)
)
)
)
)
[1] => Array
(
[id] => 2
[p_id] => 0
[name] => 分类1
[children] => Array
(
)
)
[2] => Array
(
[id] => 3
[p_id] => 0
[name] => 分类2
[children] => Array
(
)
)
[3] => Array
(
[id] => 4
[p_id] => 0
[name] => 分类3
[children] => Array
(
)
)
[4] => Array
(
[id] => 5
[p_id] => 0
[name] => 分类4
[children] => Array
(
)
)
[5] => Array
(
[id] => 6
[p_id] => 0
[name] => 分类5
[children] => Array
(
)
)
[6] => Array
(
[id] => 7
[p_id] => 0
[name] => 分类6
[children] => Array
(
)
)
[7] => Array
(
[id] => 8
[p_id] => 0
[name] => 分类7
[children] => Array
(
)
)
)
