【www.bbyears.com--php函数】
数组被作为排序函数的参数，排序以后，数组本身就发生了改变，函数的返回值为bool类型。
2 函数名中出现单a表示association，含义为，在按值排序的过程中，保持key=>value的对应关系不变
3 函数名中出现单k表示key，含义为，在按值排序的过程中按照数组key而不是数组的值排序
4 函数名中出现单r的表示reverse，含义为，按照跟不加r的相反的顺序排列
5 函数名中出现单u的表示user-defined，含义为，使用用户自定义函数排序，如果函数的逻辑是参数1<参数2返回负数，则按照升序排列(p1小2返负升)。
--------------------sort函数升序排序--------------------------------
代码如下 bool sort ( array &$array [, int $sort_flags= SORT_REGULAR ] )$fruits = array("lemon", "orange", "banana", "apple");
sort($fruits);
var_dump($fruits);
?>
结果：
array
0 => string "apple" (length=5)
1 => string "banana" (length=6)
2 => string "lemon" (length=5)
3 => string "orange" (length=6)
--------------------rsort降序排列--------------------
代码如下 $fruits = array("lemon", "orange", "banana", "apple");rsort($fruits);
var_dump($fruits);
?>
结果：
array
0 => string "orange" (length=6)
1 => string "lemon" (length=5)
2 => string "banana" (length=6)
3 => string "apple" (length=5)
---------------asort按照二维数组值的升序排列（保持key=>value的关联关系）-----------
代码如下 $fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");asort($fruits);
var_dump($fruits);
?>
结果：
array
"c" => string "apple" (length=5)
"b" => string "banana" (length=6)
"d" => string "lemon" (length=5)
"a" => string "orange" (length=6)
--------------arsort按照二维数组值的降序排列（保持key=>value的关联关系）--------------
代码如下
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
var_dump($fruits);
?>
结果
array
"a" => string "orange" (length=6)
"d" => string "lemon" (length=5)
"b" => string "banana" (length=6)
"c" => string "apple" (length=5)
--------------------ksort按照数组的key升序排列-------------- "lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
ksort($fruits);
var_dump($fruits);
?>
结果
array
"a" => string "orange" (length=6)
"b" => string "banana" (length=6)
"c" => string "apple" (length=5)
"d" => string "lemon" (length=5)
---------------------krsort按照数组key的降序排列--------------------------------
代码如下
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
krsort($fruits);
var_dump($fruits);
?>
array
"d" => string "lemon" (length=5)
"c" => string "apple" (length=5)
"b" => string "banana" (length=6)
"a" => string "orange" (length=6)
----------------usort函数按照用户自定义的函数排序----------------
function cmp($a, $b)
{
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
$a = array(3, 2, 5, 6, 1);
usort($a, "cmp");
var_dump($a);
?>
结果：
array
0 => int 1
1 => int 2
2 => int 3
3 => int 5
4 => int 6
-----------------uksort使用自定义函数按照数组的key排序-----------------
代码如下
function cmp($a, $b)
{
$a = preg_replace("@^(a|an|the) @", "", $a);
$b = preg_replace("@^(a|an|the) @", "", $b);
return strcasecmp($a, $b);
}
$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);
uksort($a, "cmp");
var_dump($a);
?>
结果：
array
"an apple" => int 3
"a banana" => int 4
"the Earth" => int 2
"John" => int 1
-------------------uasort将数组用自定义函数按照value排序，保持索引关系不变---------
代码如下
// Comparison function
function cmp($a, $b) {
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
// Array to be sorted
$array = array("a" => 4, "b" => 8, "c" => -1, "d" => -9, "e" => 2, "f" => 5, "g" => 3, "h" => -4);
var_dump($array);
// Sort and print the resulting array
uasort($array, "cmp");
var_dump($array);
?>
结果：
array
"a" => int 4
"b" => int 8
"c" => int -1
"d" => int -9
"e" => int 2
"f" => int 5
"g" => int 3
"h" => int -4
array
"d" => int -9
"h" => int -4
"c" => int -1
"e" => int 2
"g" => int 3
"a" => int 4
"f" => int 5
"b" => int 8
-------------------array_multisort排序多个数组或多维数组---------
代码如下
$ar = array(
array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);
array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC);
var_dump($ar);
?>
结果：
array
0 =>
array
0 => string "10" (length=2)
1 => int 100
2 => int 100
3 => int 11
4 => string "a" (length=1)
1 =>
array
0 => int 1
1 => int 3
2 => string "2" (length=1)
3 => int 2
4 => int 1
//说明：
1 上例中：$ar数组优先按照$ar[0]的字符串值升序排列，如果字符串值相等，再按照$ar[1]数组的数字值降序排列。
2 array_multisort函数的任意一个位置的参数如果是数组，表示排序时用的值，
如果有多个数组参数，优先按照前边的数组值进行排序，如果是常量，例如
SORT_ASC, SORT_DESC, SORT_REGULAR,SORT_NUMERIC, SORT_STRING.
表示排序方法（数组取值前优先）。