sort() 函数用于对数组单元从低到高进行排序。 rsort() 函数用于对数组单元从高到低进行排序。 asort() 函数用于对数组单元从低到高进行排序并保持索引关系。 arsort() 函数用于对数组单元从高到低进行排序并保持索引关系。 ksort() 函数用于对数组单元按照键名从低到高进行排序。 krsort() 函数用于对数组单元按照键名从高到低进行排序。例：$arr=array(23,5,26,4,9,85,10,2,55,44,21,39,11,16,55,88,421,226,588);函数名($arr);print_r($arr);
sort()： 输出：Array ( [0] => 2 [1] => 4 [2] => 5 [3] => 9 [4] => 10 [5] => 11 [6] => 16 [7] => 21 [8] => 23 [9] => 26 [10] => 39 [11] => 44 [12] => 55 [13] => 55 [14] => 85 [15] => 88 [16] => 226 [17] => 421 [18] => 588 )rsort： 输出：Array ( [0] => 588 [1] => 421 [2] => 226 [3] => 88 [4] => 85 [5] => 55 [6] => 55 [7] => 44 [8] => 39 [9] => 26 [10] => 23 [11] => 21 [12] => 16 [13] => 11 [14] => 10 [15] => 9 [16] => 5 [17] => 4 [18] => 2 )asort： 输出：Array ( [7] => 2 [3] => 4 [1] => 5 [4] => 9 [6] => 10 [12] => 11 [13] => 16 [10] => 21 [0] => 23 [2] => 26 [11] => 39 [9] => 44 [8] => 55 [14] => 55 [5] => 85 [15] => 88 [17] => 226 [16] => 421 [18] => 588 )arsort： 输出：Array ( [18] => 588 [16] => 421 [17] => 226 [15] => 88 [5] => 85 [14] => 55 [8] => 55 [9] => 44 [11] => 39 [2] => 26 [0] => 23 [10] => 21 [13] => 16 [12] => 11 [6] => 10 [4] => 9 [1] => 5 [3] => 4 [7] => 2 )ksort： 输出：Array ( [0] => 23 [1] => 5 [2] => 26 [3] => 4 [4] => 9 [5] => 85 [6] => 10 [7] => 2 [8] => 55 [9] => 44 [10] => 21 [11] => 39 [12] => 11 [13] => 16 [14] => 55 [15] => 88 [16] => 421 [17] => 226 [18] => 588 )krsort： 输出：Array ( [18] => 588 [17] => 226 [16] => 421 [15] => 88 [14] => 55 [13] => 16 [12] => 11 [11] => 39 [10] => 21 [9] => 44 [8] => 55 [7] => 2 [6] => 10 [5] => 85 [4] => 9 [3] => 4 [2] => 26 [1] => 5 [0] => 23 )