PHP中數組排序函數詳解

2024-09-04 11:46:23

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1 數組被作為排序函數的參數,排序以后,數組本身就發生了改變,函數的返回值為bool類型.

2 函數名中出現單a表示association，含義為，在按值排序的過程中，保持key=>value的對應關系不變

3 函數名中出現單k表示key，含義為，在按值排序的過程中按照數組key而不是數組的值排序

4 函數名中出現單r的表示reverse，含義為，按照跟不加r的相反的順序排列

5 函數名中出現單u的表示user-defined，含義為，使用用戶自定義函數排序，如果函數的邏輯是參數1<參數2返回負數，則按照升序排列(p1小2返負升)。

sort函數升序排序,代碼如下:

bool sort ( array &$array [, int $sort_flags= SORT_REGULAR ] )

<?php

$fruits = array("lemon", "orange", "banana", "apple");

sort($fruits);

var_dump($fruits);

//結果：

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,代碼如下:

<?php

$fruits = array("lemon", "orange", "banana", "apple");

rsort($fruits);

var_dump($fruits);

?>

//結果：

array

0 => string 'orange' (length=6)

1 => string 'lemon' (length=5)

2 => string 'banana' (length=6)

3 => string 'apple' (length=5)

asort按照二維數組值的升序排列,保持key=>value的關聯關系,代碼如下:

<?php

$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");

asort($fruits);

var_dump($fruits);

?>

//結果：

array

'c' => string 'apple' (length=5)

'b' => string 'banana' (length=6)

'd' => string 'lemon' (length=5)

'a' => string 'orange' (length=6)

arsort按照二維數組值的降序排列,保持key=>value的關聯關系,代碼如下:

<?php

$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");

arsort($fruits);

var_dump($fruits);

?>

//結果

array

'a' => string 'orange' (length=6)

'd' => string 'lemon' (length=5)

'b' => string 'banana' (length=6)

'c' => string 'apple' (length=5)

ksort按照數組的key升序排列,代碼如下:

<?php

$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");

ksort($fruits);

var_dump($fruits);

?>

//結果

array

'a' => string 'orange' (length=6)

'b' => string 'banana' (length=6)

'c' => string 'apple' (length=5)

'd' => string 'lemon' (length=5)

krsort按照數組key的降序排列,代碼如下:

<?php

$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");

krsort($fruits);

var_dump($fruits);

?>

//開源代碼Vevb.com

array

'd' => string 'lemon' (length=5)

'c' => string 'apple' (length=5)

'b' => string 'banana' (length=6)

'a' => string 'orange' (length=6)

usort函數按照用戶自定義的函數排序,代碼如下:

<?php

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);

?>

//結果：

array

0 => int 1

1 => int 2

2 => int 3

3 => int 5

4 => int 6

uksort使用自定義函數按照數組的key排序,代碼如下:

<?php

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);

?>

//結果：

array

'an apple' => int 3

'a banana' => int 4

'the Earth' => int 2

'John' => int 1

uasort將數組用自定義函數按照value排序,保持索引關系不變,代碼如下:

<?php

// 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);

?>

//結果：

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排序多個數組或多維數組,代碼如下:

<?php

$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);

?>

//結果：

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