PHP 介紹所有陣列排序

在這裡介紹所有PHP排序陣列的功能

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

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

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

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

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

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

參考資料：

PHP Array

PHP 介紹所有 陣列 排序

PHP sort an array

PHP 介紹所有陣列排序