本文实例讲述了PHP实现无限极分类生成分类树的方法。分享给大家供大家参考，具体如下：
现在的分类数据库设计基本都是：每一个分类有一个id主键字段，一个pid指向父类的id，这样便可实现无限级分类，取出的数据就是如下的格式：
$arr = array( array("id" => 1 , "pid" => 0 , 'cat' => '栏目一'), array("id" => 2 , "pid" => 0 , 'cat' => '栏目二'), array("id" => 3 , "pid" => 1 , 'cat' => '栏目三'), array("id" => 4 , "pid" => 2 , 'cat' => '栏目四'), array("id" => 5 , "pid" => 1 , 'cat' => '栏目五'), array("id" => 6 , "pid" => 5 , 'cat' => '栏目六'), array("id" => 7 , "pid" => 5 , 'cat' => '栏目七'), array("id" => 8 , "pid" => 6 , 'cat' => '栏目八'), array("id" => 9 , "pid" => 1 , 'cat' => '栏目九'), array("id" => 10 , "pid" => 0 , 'cat' => '栏目十'), array("id" => 11 , "pid" => 10 , 'cat' => '栏目十一'), array("id" => 12 , "pid" => 11 , 'cat' => '栏目十二'), array("id" => 13 , "pid" => 2 , 'cat' => '栏目十三'), array("id" => 14, "pid" => 13 , 'cat' => '栏目十四'));不多说，直接上处理代码：
//生成无限极分类树function make_tree($arr){ $refer = array(); $tree = array(); foreach($arr as $k => $v){ $refer[$v['id']] = & $arr[$k]; //创建主键的数组引用 } foreach($arr as $k => $v){ $pid = $v['pid']; //获取当前分类的父级id if($pid == 0){ $tree[] = & $arr[$k]; //顶级栏目 }else{ if(isset($refer[$pid])){ $refer[$pid]['subcat'][] = & $arr[$k]; //如果存在父级栏目，则添加进父级栏目的子栏目数组中 } } } return $tree;}测试运行：
$cat = make_tree($arr);print_r($cat);
运行结果：
Array( [0] => Array ( [id] => 1 [pid] => 0 [cat] => 栏目一 [subcat] => Array ( [0] => Array ( [id] => 3 [pid] => 1 [cat] => 栏目三 ) [1] => Array ( [id] => 5 [pid] => 1 [cat] => 栏目五 [subcat] => Array ( [0] => Array ( [id] => 6 [pid] => 5 [cat] => 栏目六 [subcat] => Array ( [0] => Array ( [id] => 8 [pid] => 6 [cat] => 栏目八 ) ) ) [1] => Array ( [id] => 7 [pid] => 5 [cat] => 栏目七 ) ) ) [2] => Array ( [id] => 9 [pid] => 1 [cat] => 栏目九 ) ) ) [1] => Array ( [id] => 2 [pid] => 0 [cat] => 栏目二 [subcat] => Array ( [0] => Array ( [id] => 4 [pid] => 2 [cat] => 栏目四 ) [1] => Array ( [id] => 13 [pid] => 2 [cat] => 栏目十三 [subcat] => Array ( [0] => Array ( [id] => 14 [pid] => 13 [cat] => 栏目十四 ) ) ) ) ) [2] => Array ( [id] => 10 [pid] => 0 [cat] => 栏目十 [subcat] => Array ( [0] => Array ( [id] => 11 [pid] => 10 [cat] => 栏目十一 [subcat] => Array ( [0] => Array ( [id] => 12 [pid] => 11 [cat] => 栏目十二 ) ) ) ) ))
如果大家需要这样的组装格式，或者需要该格式方便后续的处理，可以尝试此方法
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希望本文所述对大家PHP程序设计有所帮助。
