Generate random key

[Mythotical]

I haven't figured out yet how to generate a random key that consists of letters and numbers. I managed to get it to generate numbers but for the life of me I can't seem to figure out how to generate a random alphanumeric key.

Here is what I am using for numeric only:

PHP Code:

mt_rand(); 


I know, thats simple, but I am using it temporarily till I figure out how to generate a key that consists of alphanumeric and is length is 16, no matter how many key's it generates.

Any help greatly appreciated

EDIT: Also, I have read quite a few articles on php.net but alas have come up empty handed.

Thanks in advance
Steve M

[MoT3rror]

This page should help you.
http://www.i-fubar.com/random-string-generator.php

[Hossie]

Is the link a joke? 2 lines are enough:

PHP Code:

<?php
function randomstr($length){
  for($i=0; $i<$length; $i++)$str[$i]=chr(rand(97, 122));
  return implode("", $str);
}
echo randomstr(16);
?>

[Mythotical]

Thanks MoT3rror and Hossie.

Hossie, what you gave me worked but it gave me a 16 letter string. I need it to be a mix of letters and numbers.

[Hossie]

So why don't you just use some hash algorithm?

PHP Code:

<?php
function randomstr($length){
  return substr(md5(time()*rand(1, 100)), 0, $length);
}
echo randomstr(16);
?>

[Mythotical]

Perfect, thats what I was trying to figure out last night but couldn't. You just saved me a headache Hossie. Thanks.

That link above though seemed good but alot of lines of code. Glad you made a post.

[MoT3rror]

You must not have read the first part of the page.

PHP Code:

function assign_rand_value($num)
{
// accepts 1 - 36
  switch($num)
  {
    case "1":
     $rand_value = "a";
    break;
    case "2":
     $rand_value = "b";
    break;
    case "3":
     $rand_value = "c";
    break;
    case "4":
     $rand_value = "d";
    break;
    case "5":
     $rand_value = "e";
    break;
    case "6":
     $rand_value = "f";
    break;
    case "7":
     $rand_value = "g";
    break;
    case "8":
     $rand_value = "h";
    break;
    case "9":
     $rand_value = "i";
    break;
    case "10":
     $rand_value = "j";
    break;
    case "11":
     $rand_value = "k";
    break;
    case "12":
     $rand_value = "l";
    break;
    case "13":
     $rand_value = "m";
    break;
    case "14":
     $rand_value = "n";
    break;
    case "15":
     $rand_value = "o";
    break;
    case "16":
     $rand_value = "p";
    break;
    case "17":
     $rand_value = "q";
    break;
    case "18":
     $rand_value = "r";
    break;
    case "19":
     $rand_value = "s";
    break;
    case "20":
     $rand_value = "t";
    break;
    case "21":
     $rand_value = "u";
    break;
    case "22":
     $rand_value = "v";
    break;
    case "23":
     $rand_value = "w";
    break;
    case "24":
     $rand_value = "x";
    break;
    case "25":
     $rand_value = "y";
    break;
    case "26":
     $rand_value = "z";
    break;
    case "27":
     $rand_value = "0";
    break;
    case "28":
     $rand_value = "1";
    break;
    case "29":
     $rand_value = "2";
    break;
    case "30":
     $rand_value = "3";
    break;
    case "31":
     $rand_value = "4";
    break;
    case "32":
     $rand_value = "5";
    break;
    case "33":
     $rand_value = "6";
    break;
    case "34":
     $rand_value = "7";
    break;
    case "35":
     $rand_value = "8";
    break;
    case "36":
     $rand_value = "9";
    break;
  }
return $rand_value;
} 


This function defines what the random characters going to be.

The second funtion.

PHP Code:

function get_rand_id($length)
{
  if($length>0) 
  { 
  $rand_id="";
   for($i=1; $i<=$length; $i++)
   {
   mt_srand((double)microtime() * 1000000);
   $num = mt_rand(1,36);
   $rand_id .= assign_rand_value($num);
   }
  }
return $rand_id;
} 


This function uses the characters and numbers to output a random string on letters and numbers.

Call on this to come with 16.

PHP Code:

get_rand_id(16); 


Using one of the hashing algorithms would be the most efficient solution - that is what hashing is for.