PHP random number principle

php random number principle:

##The system automatically generates a random number seed (mt_srand The function can generate seeds by itself), mt_rand first determines whether there is a generated seed, if not, it automatically generates one, and then generates a random number based on the seed.

Generate 10000-99999 random numbers: (Recommended learning:

PHP programming from entry to proficiency)

mt_rand(10000,99999);    
//php提供的随机数为伪随机数(计算机只能生成伪随机数,php英文文档上有警告此随机数不要使用于token生成的操作)
//伪随机是由可确定的函数（常用线性同余），通过一个种子（常用时钟），产生的伪随机数。

A small experiment:

mt_srand(10);    //播种随机数种子
echo mt_rand(1,100).PHP_EOL;   //生成随机数
echo mt_rand(1,100).PHP_EOL;   //生成随机数
//然后你会发现无论你怎么刷新网页，生成的随机数都是一样的!!
//建议使用openssl_random_pseudo_bytes生成token

Explode the random number seed and use the tool php_mt_srand

to generate a random string number:

$chars  = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$chars .= &#39;`~!@#$%^&*()_+-=[]{};:"|,.<>/?&#39;;
$str=substr(str_shuffle($chars),0,10);    //10位随机数
//中英文混合随机可以会出现乱码因为str_shuffle是基于字符随机打乱
//不能直接使用str_split函数，因为该函数也是基于字符串的
//PS:疯狂吐槽中文
function mb_str_split($str){    //切割中文字符串
    return preg_split(&#39;/(?<!^)(?!$)/u&#39;, $str );
}
$chars.=&#39;你好歹还得发哈收到付款将很快经过艰苦规划&#39;;
$chars=mb_str_split($chars);
//可以使用数组随机数array_rand(array,number)

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