如何生成随机唯一字符串列表？ [关闭]

Question

I'm using this function to create a random string, but how would I make it to generate a unique string list for a 500 strings?

function generateRandomString($length = 8) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, strlen($characters) - 1)];
    }
    return $randomString;
}

Answer 1

If you are worry about inserted rows in table then there are 3 simple ways to do it.

First way, you can check if the string exists in db then create another random string.

Second way, use UUID() function of mysql that generates random value and there's no need to worry about duplication.

Third way, if you want the array, generate 500 string and put in an array. then use array_unique() to remove duplication. If array length was < 500 then generate more (for example 12 strings) then check if < 500 again and again until it reaches exactly 500. Checking can be done in a while loop or so.

while( count($arr) < 500 )
{
    $arr[] = generateRandomString();

    if( count($arr) == 500 )
        $arr = array_unique( $arr );

}