Creating a random estimate string in php

Question

I need to create a auto incrementing string similar to this randomly via php. The string is like this. So what i need is a mix of numbers and letter that is randomally generated and doesnt have to be sequential just as long as its random like this 823N9823 and it has 8 characters max

Answer 1

If the characters don't need to be unique:

function randomString($length = 8, $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789') {
    $randomString = '';
    $numofChars = strlen($chars);
    while (--$length) {
        $randomString .= $chars[mt_rand(0, $numofChars - 1)];
    }
    return $randomString;
}

If the characters must be unique:

function randomString($length = 8, $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789') {
    return substr(str_shuffle($chars), 0, 8);
}

Answer 2

usage:

echo generateRandomName();

function:

function generateRandomName($length=8,$level=2){

   list($usec, $sec) = explode(' ', microtime());
   srand((float) $sec + ((float) $usec * 100000));

   $validchars[1] = "0123456789abcdfghjkmnpqrstvwxyz";
   $validchars[2] = "0123456789abcdfghjkmnpqrstvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
   $validchars[3] = "0123456789_!@#$%&*()-=+/abcdfghjkmnpqrstvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_!@#$%&*()-=+/";

   $password  = "";
   $counter   = 0;

   while ($counter < $length) {
     $actChar = substr($validchars[$level], rand(0, strlen($validchars[$level])-1), 1);

     // All character must be different
     if (!strstr($password, $actChar)) {
        $password .= $actChar;
        $counter++;
     }
   }

   return $password;

}

Found on PHPToys

Level the level of characters to be used, 3 have special chars as $validchars[3] has.

You also can call it as: generateRandomName(5) to generate a name with length of 5.

Answer 3

function generateRandomString($length=8, $characters='abcdefghijklmnopqrstuvwxyz0123456789'){
   $str = '';
   $len = strlen($characters);
   for($i=0; $i<length; $i++){
      $str .= $characters[mt_rand(0, $len)];
   }
   return $string;
}

Usage:

//generates a random string, using defaults: length = 8 and characters = a-z, 0-9
echo "Your password: " . generateRandomString();
//custom length: 10
echo "Thingeys: " . generateRandomString(10);
//digits only, length 4
echo "Your PIN: " . generateRandomString(4, '0123456789');

Answer 4

You can use mt_rand() to generate a random integer and then transform the values into a string. The function below will give you 2 821 109 907 456 possible values.

function random_id($length = 8) {
  $validChars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';

  $rndString = '';

  for($i = 0; $i < $length; $i++) {
    $rndString .= $validChars[mt_rand(0, strlen($validChars) - 1)];
  }

  return $rndString;
}

$lengthEight = random_id();
$lengthTen = random_id(10);

Since there are more letters and numbers in the list of possible characters, you'll usually get a string with more letters then numbers.

If you want to skew the results towards a string with more numbers then letters, then you can use the following:

function skewed_random_id($numericFactor = 0.8, $length = 8) {
  $validAlpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  $validNumeric = '0123456789';

  $rndString = '';

  for($i = 0; $i < $length; $i++) {
    if((mt_rand() / mt_getrandmax()) < $numericFactor) {
      $rndString .= $validNumeric[mt_rand(0, strlen($validNumeric) - 1)];
    } else {
      $rndString .= $validAlpha[mt_rand(0, strlen($validAlpha) - 1)];
    }
  }

  return $rndString;
}

$eightyPercentNumeric = skewed_random_id();
$fiftyFifty = skewed_random_id(0.5);
$allAlpha = skewed_random_id(0);
$allNumeric = skewed_random_id(1);

Answer 5

echo substr(str_replace(array('/', '+'), '', base64_encode(sha1(uniqid(), true))), 0, 8);

Sample output:

LTeQpy9p
v11oy9R7
TjdkXZru
lh3TvNi4
X5Ca0ZXS
L01RfhxW
QDfwNnGO

you can use strtoupper and strtolower to get a version that suits your needs.

---

EDIT:

If you are gonna use this for something critical rather than just wanting a random string, change uniqid() into mt_rand():

echo substr(str_replace(array('/', '+'), '', base64_encode(sha1(
    mt_rand(). '.'. mt_rand(). '.'. mt_rand()%4 //256^8 of input possibilities (8 bytes)
, true))), 0, 8);

Answer 6

substr(uniqid(), 0, 8);

http://php.net/uniqid