shuffle() 函数

把数组中的元素按随机顺序重新排序：
$my_array = array("red","green","blue","yellow","purple");shuffle($my_array);
print_r($my_array);

运行结果:
Array ( [0] => purple [1] => blue [2] => yellow [3] => red [4] => green )
 
range() 函数

创建一个包含从 "0" 到 "5" 之间的元素范围的数组：
$my_array = array("red","green","blue","yellow","purple");
shuffle($my_array);
print_r($my_array);

运行结果:
Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 )

返回包含 "0" 至 "50" 之间并以 10 递增的元素的数组：
$number = range(0,50,10);
print_r ($number);
运行结果:
Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 )

使用字母 - 返回包含从 "a" 到 "d" 之间的元素的数组：
$letter = range("a","d");
print_r ($letter);
运行结果:
Array ( [0] => a [1] => b [2] => c [3] => d )

rand() 函数返回随机整数