mkdir（）不使用此代码为上传照片创建随机目录名称

// profile picture upload
if (isset($_FILES['profilepic'])) {
    if ( ((@$_FILES["profilepic"]["type"]=="image/jpeg")
            || (@$_FILES["profilepic"]["type"]=="image/png")
            || (@$_FILES["profilepic"]["type"]=="image/gif"))
        && (@$_FILES["profilepic"]["size"] < 1048576) ) //1 Megabyte
    {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        $rand_dir_name = substr(str_shuffle($chars), 0, 15);

        mkdir("userdata/profile_pics/$rand_dir_name");

This is the directory all my files are: C:/xampp/htdocs/asweb

And this is where I want to keep the new directory: C:/xampp/htdocs/asweb/userdata/profile_pics

I just tested the following:

$chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
$rand_dir_name = substr(str_shuffle($chars), 0, 15);
echo $rand_dir_name.$b;    // ojTxNHb0RuiyKze

mkdir("c:\\dev\\".$rand_dir_name,0777,TRUE);

It made c:\dev\ojTxNHb0RuiyKze no problem. I went in there and saved a text file.

The Manual page says

mode

The mode is 0777 by default, which means the widest possible access. For more information on modes, read the details on the chmod() page.

Note: mode is ignored on Windows. Note that you probably want to specify the mode as an octal number, which means it should have a leading zero. The mode is also modified by the current umask, which you can change using umask().

However on linux, have it follow chmod values.

Edit: op can't do it, here we go again:

$chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
$rand_dir_name = substr(str_shuffle($chars), 0, 15);
echo $rand_dir_name.$b;    // l1TGXW3kgQcr2N5
mkdir("C:\\xampp\\htdocs\\asweb\\userdata\\profile_pics\\".$rand_dir_name,0777,TRUE);   

made C:\xampp\htdocs\asweb\userdata\profile_pics\l1TGXW3kgQcr2N5 no problem