飛朵啦學習手札

有時候會用到陣列的排序，這邊做個mark

主要轉自：http://www.kikinote.com/article/699.html

同時也可以參考：http://tw2.php.net/manual/en/function.asort.php

在這裡介紹所有PHP排序陣列的功能

1. sort：排序「值」，從小到大 (Sort an array)

     $tempArray = array(5,8,1,2,7,6,3,4);
     sort($tempArray);
     #結果會是 1 2 3 4 5 6 7 8

2. rsort：排序「值」，從大到小 (Sort an array in reverse order)

     $tempArray = array(5,8,1,2,7,6,3,4);
     rsort($tempArray);
     #結果會是 8 7 6 5 4 3 2 1

3. ksort：排序「Key」，從小到大 (Sort an array by key)

     #這個例子要用key value的格式會比較好理解
     $tempArray = array(
       "b" => "Marry",
       "c" => "Jack",
       "a" => "Rich",
       "d" => "Jason"  
     );
     ksort($tempArray);
     #結果會是 a => "Rich", b => "Marry", c => "Jack", d => "Jason"
     #注意到了嗎？他是按照key來做排序，並不是按照值喔

4. krsort：排序「Key」，從大到小 (Sort an array by key in reverse ordery)

     $tempArray = array(
       "b" => "Marry",
       "c" => "Jack",
       "a" => "Rich",
       "d" => "Jason"  
     );
     krsort($tempArray);
     #結果會是 d => "Jason", c => "Jack",  b => "Marry", a => "Rich"
     #這是做key的反向排序

5. asort：排序「值」，從大到小，且保留原本的index
   (Sort an array and maintain index association)
   這是什麼意思？ asort跟sort很像，差別在sort之後會改變原本的index順序，而asort會保留原本的index

    

     //比較sort 與 asort
     $tempArray = array("e","h","a","b","g","f","c","d");
     sort($tempArray);
     #結果會是 0=>a, 1=>b, 2=>c, 3=>d, 4=>e, 5=>f, 6=>g, 7=>h
     #index的順序是從0-7
     //而asort會保留排序之前的index位置
     $tempArray = array("e","h","a","b","g","f","c","d");
     asort($tempArray);
     #結果會是 2=>a, 3=>b, 6=>c, 7=>d, 0=>e, 5=>f, 4=>g, 1=>h
     #index的順序是從就不是0-7了，變成 2 3 6 7 0 5 4 1

6. arsort：排序「值」，從小到大，且保留原本的index
   (Sort an array in reverse order and maintain index association)

    

     $tempArray = array("e","h","a","b","g","f","c","d");
     arsort($tempArray);
     #結果會是 1=>h, 4=>g, 5=>f, 0=>e, 7=>d, 6=>c, 3=>b, 2=>a