How can I make short random unique keys, like YouTube video IDs, in PHP? [closed]

Answer 1

Here is a small function that generates unique key randomly each time. It has very fewer chances to repeat same unique ID.

function uniqueKey($limit = 10) {

    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    $randstring = '';

    for ($i = 0; $i < $limit; $i++) {

        $randstring .= $characters[rand(0, strlen($characters))];
    }

    return $randstring;
}

source: http://guruquest.net/question/how-to-generate-random-unique-ids-like-youtube-or-tinyurl-in-php/

Answer 2

all the methods above are good but make sure you know and not assume the generated string is unique. What I have done in the past is made a recursive function that checks the string against my database and if it is unique it returns the value, otherwise it just runs again. This will hardly happen though depending how long your unique string is. Its just good to know its unique.

Answer 3

The idea is to convert a unique integer (such as current time) in an other mathematical base.

A very simple way in PHP :

// With this precision (microsecond) ID will looks like '2di2adajgq6h'

// From PHP 7.4.0 this is needed, otherwise a warning is displayed
$cleanNumber = preg_replace( '/[^0-9]/', '', microtime(false) );
$id = base_convert($cleanNumber, 10, 36);


// With less precision (second) ID will looks like 'niu7pj'

$id = base_convert(time(), 10, 36);

Answer 4

<?php
function keygen(){
    $chars = "bcdfghjklmnpqrstvwxyz";
    $chars .= "BCDFGHJKLMNPQRSTVWXYZ";
    $chars .= "0123456789";
    while(1){
        $key = '';
        srand((double)microtime()*1000000);
        for($i = 0; $i < 10; $i++){
            $key .= substr($chars,(rand()%(strlen($chars))), 1);
        }
        break;
    }
    return $key;
}

//echo keygen();
?>

Answer 5

For most purposes uniqid will suffice, if you need to make sure there's absolutely no clash, more convoluted measures are necessary.

Answer 6

From comments on here:

<?php 
function generateRandStr($length){ 
      $randstr = ""; 
      for($i=0; $i<$length; $i++){ 
         $randnum = mt_rand(0,61); 
         if($randnum < 10){ 
            $randstr .= chr($randnum+48); 
         }else if($randnum < 36){ 
            $randstr .= chr($randnum+55); 
         }else{ 
            $randstr .= chr($randnum+61); 
         } 
      } 
      return $randstr; 
   } 
?> 

Simply use: 
generateRandStr(10); 

Sample output: $%29zon(4f

You can mess around with this function to generate just alphanumeric, or just alphabetic characters.