03.PHP-随机打印输出字符串

<?php
$str = "0123456789abcdefghijklmnobqrstuvwxyzABCDEFGHIJKLMNOBQRSTUVWXYZ";
$num = 4;//随机字符长度
function get_random_str($str,$num){
    $rand_str = '';
    $len = strlen($str) - 1;
    for($i = 0;$i < $num;$i++){
        //通过随机函数获取单个字符
        $rand_str .= $str[rand(0,$len)];
    }
    return $rand_str;
}
echo get_random_str($str,$num);

效果：A4Bu