首先讲下一维数组的排序函数:
常用函数:sort() 按照键值(value)对关联数组进行升序排序;
$arr=["a"=>4,"b"=>2,"c"=>8,"d"=>"6"];
sort($arr);
echo "<pre>";print_r($arr);
Array
(
[0] => 2
[1] => 4
[2] => 6
[3] => 8
)
ksort() 按照键名(key)对关联数组进行升序排序;
$arr=["a"=>4,"b"=>2,"c"=>8,"d"=>"6"];
ksort($arr);
echo "<pre>";
print_r($arr);
按键名排序输出:
Array
(
[a] => 4
[b] => 2
[c] => 8
[d] => 6
)
二维数组排序函数 usort uksort uasort (后面可以跟自定义函数名)
function my_sort($a,$b)
{ //返回 0 -1 1
if ($a['key1']==$b['key1']) return 0;
return ($a['key1']<$b['key1'])?-1:1;
}
$arr = [
['key1' => 10, 'key2' => 'linux'],
['key1' => 20, 'key2' => 'mysql'],
['key1' => 9, 'key2' => 'php']
];
usort($arr, 'my_sort'); //自定义函数 usort 根据数值进行排序,但并不会保存关键字
echo "<pre>";
print_r($arr);
Array
(
[0] => Array
(
[key1] => 9
[key2] => php
)
[1] => Array
(
[key1] => 10
[key2] => linux
)
[2] => Array
(
[key1] => 20
[key2] => mysql
)
)
uksort($arr, 'my_sort'); //排序将基于关键字
echo "<pre>";
print_r($arr);
Array
(
[2] => Array
(
[key1] => 9
[key2] => php
)
[1] => Array
(
[key1] => 20
[key2] => mysql
)
[0] => Array
(
[key1] => 10
[key2] => linux
)
)
uasort($arr, 'my_sort'); //uasort 关键字就会被保存
echo "<pre>";
print_r($arr);
Array
(
[2] => Array
(
[key1] => 9
[key2] => php
)
[0] => Array
(
[key1] => 10
[key2] => linux
)
[1] => Array
(
[key1] => 20
[key2] => mysql
)
)
由以上例子可以看出 sort asort ksort都是针对一维数组的,并且sort asort根据值升序;
usort uasort uksort 根据二维数组排序,并且usort uasort根据值排序,uasort保留本身键名,uksort根据键名排序