PHP Recursive instance

Source: Internet
Author: User

Recursion as an algorithm is widely used in programming language. A procedure or function has a method of directly or indirectly invoking itself in its definition or description, which usually transforms a large and complex problem layer into a smaller problem similar to the original problem, and the recursive strategy can describe the repeated computations needed in the process of solving the problems by a small number of programs. Greatly reduces the code volume of the program.

Here are 4 examples of recursion:

 $V) {if (Is_array ($v)) {$sum + = funtmp ($v, $sum);        }} return $sum;    } return Funtmp ($arr);    }//$arr = Array (1,2,3,4,array (1,2,3,array (0,3))); echo Conarr ($arr). '
';    //echo Count ($arr, 1);    /**    * Recursive statistics the number of sub-files in the specified directory and the number of folders      * @param $dirname string directory path     * @return Array|boolean Returns an array that contains the number of child files and the number of folders, failed to return false     */    function Condir ($dirname, $data = Array (' Dirnum ' =>0, ' FileNum ' =>0)) {         if (!is_dir ($dirname)) {             return false;        }         $dir = Opendir ($dirname); Open handle         readdir ($dir);//Read points         readdir ($dir) ;//Read points         while ($filename = Readdir ($dir)) {              $newfile = $dirname. ' /'. $filename;//splicing sub-file name             if (Is_dir ($newfile)) {                 $data [' Dirnum ']++;                 $data [ ' Dirnum ']+=condir ($newfile) [' Dirnum '];                 $data [' FileNum ']+=condir ($newfile) [' FileNum '];            }else{                  $data [' FileNum ']++;             }        }         return $data;    }    //$a =  condir (' C:\wamp\www\test ');    //var _dump ($a);    /**    * Delete file or folder     * @param string $dirname file path  & nbsp  * @return Boolean Delete successfully returns TRUE, Failure returns false    */    function Deldir ($dirname) {         if (!file_exists ($dirname)) {return false;}         if ($dir = Opendir ($dirname)) {            while ($filename = Readdir ($dir)) {                 if ($filename! = "." && $filename! = ' ... ') {                     $subFile = $dirname. ' /'. $filename;                    if (is_ Dir ($subFile)) {                         deldir ($subFile);                     }                     if (Is_file ($subFile)) {                        unlink ($subFile);                     }                 }            }                 closedir ($dir);             rmdir ($dirname);        }         if (!file_exists ($dirname)) {            return true;         }else{            return false;         }    }    //echo deldir (' C:\wamp\www\test ');     //infinite pole sorting, parent class followed by subclass     function GetList ($cate, $pid =0, $html = "------", $i =0) {         $i ++;        $list = Array ();        foreach ($cate as $val) {             if ($val [' pid ']== $pid) {                 $val [' HTML ']=str_repeat ($html, $i-1);                 $list []= $val;                 $list = Array_merge ($list, GetList ($cate, $val [' id '], $html, $i));            }       }         return $list;   }?>

The above describes the PHP recursive instance, including the aspects of the content, I hope that the PHP tutorial interested in a friend helpful.

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