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

更多关于PHP相关内容感兴趣的读者可查看本站专题：《PHP数据结构与算法教程》、《php程序设计算法总结》、《PHP常用遍历算法与技巧总结》、《PHP数学运算技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》及《php常见数据库操作技巧汇总》

希望本文所述对大家PHP程序设计有所帮助。