Detailed explanation of array sorting function in PHP_PHP tutorial
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Release: 2016-07-20 11:11:07
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PHP comes with a large number of array sorting functions. Let’s introduce the usage of PHP array sorting one by one.
The array is used as a parameter of the sorting function. After sorting, the array itself changes, and the return value of the function is of type bool.
2 The single a appearing in the function name means association, which means that in the process of sorting by value, the corresponding relationship of key=>value remains unchanged
3 The single a appearing in the function name means association. k represents key, which means that in the process of sorting by value, the array key is sorted instead of the value of the array
4 A single r appearing in the function name represents reverse, which means that the order is the opposite of that without r. The order of
5 The single u appearing in the function name means user-defined, which means that the user-defined function is used to sort. If the logic of the function is that parameter 1
--------------------sort function ascending order-------------------- ------------
$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);
uksort($a, "cmp");
var_dump($a); ?> 结果: array 'an apple' => int 3 'a banana' => int 4 'the Earth' => int 2 'John' => int 1
'c' => string 'apple' (length=5)--------------------ksort is in ascending order according to the key of the array Arrangement-------------- "lemon", "a"=>"orange", "b"=> "banana", "c"=>"apple");ksort($fruits);var_dump($fruits);?>resultarray 'a' => string 'orange' (length=6)'b' => string 'banana' (length=6)'c' => string 'apple' (length=5 )'d' => string 'lemon' (length=5)
------------- --------krsort sorts the array keys in descending order--------------------------------
// Sort and print the resulting array uasort($array, 'cmp'); var_dump($array); ?> 结果: array 'a' => int 4 'b' => int 8 'c' => int -1 'd' => int -9 'e' => int 2 'f' => int 5 'g' => int 3 'h' => int -4 array 'd' => int -9 'h' => int -4 'c' => int -1 'e' => int 2 'g' => int 3 'a' => int 4 'f' => int 5 'b' => int 8
// Comparison function function cmp($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);
?> Result: array
'a' => int 4
'b' => int 8'c' = > int -1'd' => int -9'e' => int 2'f' => int 5'g' => int 3 'h' => int -4array'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 Sort multiple arrays or multi-dimensional arrays- --------
The code is as follows
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$ar = array(<🎜>array("10", 11, 100, 100, "a"),<🎜> array( 1, 2, "2", 3, 1)<🎜>);<🎜><🎜>array_multisort($ar[0], SORT_ASC, SORT_STRING,<🎜>$ar[1], SORT_NUMERIC, SORT_DESC) ;<🎜>var_dump($ar);<🎜>?>Result: array0 => array0 => string '10' (length= 2)1 => int 1002 => int 1003 => int 114 => string 'a' (length=1)1 = > array0 => int 1 1 => int 32 => string '2' (length= 1)3 => int 24 => int 1//Explanation: 1 In the above example: the $ar array is prioritized in ascending order according to the string value of $ar[0] Arrange, if the string values are equal, then sort according to the numeric value of the $ar[1] array in descending order. 2 If the parameter at any position of the array_multisort function is an array, it represents the value used for sorting. If there are multiple array parameters, the previous array value will be sorted first. If it is a constant, such as SORT_ASC, SORT_DESC, SORT_REGULAR,SORT_NUMERIC, SORT_STRING. indicates the sorting method (array values are taken first).
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