PHP non-repeating random number generation method_PHP tutorial

The principle is very simple. First write a function to generate one of the 36 characters 0-z. Each call to the getOptions() method generates a character, which is stored as follows: array[0] = 0, array[1] = 1, …, array[35] = z.

Array ( 
	[0] => 0 
	[1] => 1 
	[2] => 2 
	[3] => 3 
	[4] => 4 
	[5] => 5 
	[6] => 6 
	[7] => 7 
	[8] => 8 
	[9] => 9 
	[10] => a 
	[11] => b 
	[12] => c 
	[13] => d 
	[14] => e 
	[15] => f 
	[16] => g 
	[17] => h 
	[18] => i 
	[19] => j 
	[20] => k 
	[21] => l 
	[22] => m 
	[23] => n 
	[24] => o 
	[25] => p 
	[26] => q 
	[27] => r 
	[28] => s 
	[29] => t 
	[30] => u 
	[31] => v 
	[32] => w 
	[33] => x 
	[34] => y 
	[35] => z 
)

Then randomly generate a number between 0-35 as the index, which is actually to randomly pick out a number from the above array as the first character in the variable $result. This random index will then be assigned as the last one in the array, and it will not participate in the next round of random selection.

<?php
// 生成0123456789abcdefghijklmnopqrstuvwxyz中的一个字符
function getOptions()
{
 	$options = array();
 	$result = array();
 	for($i=48; $i<=57; $i++)
 	{
     	array_push($options,chr($i));  
 	}
 	for($i=65; $i<=90; $i++)
  	{
      	$j = 32;
      	$small = $i + $j;
      	array_push($options,chr($small));
	}
 	return $options;
}
/*
$e = getOptions();
for($j=0; $j<150; $j++)
{
	echo $e[$j];
}
*/
$len = 10;
// 随机生成数组索引，从而实现随机数
for($j=0; $j<100; $j++)
{
 	$result = "";
 	$options = getOptions();
 	$lastIndex = 35;
 	while (strlen($result)<$len)
 	{
  		// 从0到35中随机取一个作为索引
		$index = rand(0,$lastIndex);
		// 将随机数赋给变量 $chr
  		$chr = $options[$index];
		// 随机数作为 $result 的一部分
  		$result .= $chr;
  		$lastIndex = $lastIndex-1;
		// 最后一个索引将不会参与下一次随机抽奖
  		$options[$index] = $options[$lastIndex];
 	}
 	echo $result."n";
}
?>

http://www.bkjia.com/PHPjc/752456.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/752456.htmlTechArticleThe principle is very simple. First write a function to generate one of the 36 characters 0-z. Each call to the getOptions() method generates a character, and they are stored as follows: array[0] = 0, array[1] = 1...