One-line PHP random string generator?

Is there a probability that the first is ever a number? i executed the it about 50 times and got a number as first character but happened once 30128fb9b80c5697a4a3954b96e1295

Uours Over a year ago

I cannot see any reason except if the values in the mt_rand are not correct . I think it should be mt_rand(0, 50) . It was mt_rand(0, 51) previously .

Perhaps you are right, the first char is 0, I will now only use lower case chars, since the alphabet has 26 letters then the max param should be 25

Uours Over a year ago

With my corrected solution I have generated 100,000 strings and none of those started with numeric character . I have tested the lowercase solution for 100,000 strings and the solution seemed perfect .

Awesome, what did you use to generate the strings, also, just wondering how to benchmark my self the performance of these codes? any advice would be awesome

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23k · Accepted Answer · 2013-10-25 13:18:05Z

30

I had found something like this:

$length = 10;
$randomString = substr(str_shuffle(md5(time())),0,$length);
echo $randomString;

answered Oct 25, 2013 at 13:18

23k

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1 Comment

mrmut Over a year ago

This is better version than the one above, as it is aways unique and has char lenght in it.

maaarghk · Accepted Answer · 2014-09-04 08:54:38Z

7

I decided this question needs a better answer. Like code golf! This also uses a better random byte generator.

preg_replace("/[\/=+]/", "", base64_encode(openssl_random_pseudo_bytes(8)));

Increase the number of bytes for a longer password, obviously.

answered Sep 4, 2014 at 8:54

maaarghk

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Rudie Over a year ago

You could use str_replace(array('/', '=', '+'), '', ..., that might be faster.

PRNDL Development Studios · Accepted Answer · 2013-09-26 01:10:33Z

6

If you need it to start with a letter, you could do this. It's messy... but it's one line.

$randomString = substr(str_shuffle("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 1) . substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 10);

echo $randomString;

answered Sep 26, 2013 at 1:10

PRNDL Development Studios

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11 Comments

He never said it needed to be alfanumeric.

@Alix Axel: what do you actually mean?

You don't need the second str_shuffle.

actually it can be alphanumeric, however the first character needs to be an alphabet letter]

@Alix Axel: there won't be numbers then in the left part of string. OP expects it to be alpha-numeric except of the first character. That's obvious from base64 part of the question.

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Community · Accepted Answer · 2017-05-23 11:46:51Z

4

Creates a 200 char long hexdec string:

$string = bin2hex(openssl_random_pseudo_bytes(100));

maaarghk's answer is better though.

edited May 23, 2017 at 11:46

CommunityBot

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answered Sep 4, 2014 at 18:26

Rudie

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Comments

Daniel Reyes · Accepted Answer · 2014-05-25 05:08:49Z

3

base_convert(microtime(true), 10, 36);

answered May 25, 2014 at 5:08

Daniel Reyes

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1 Comment

Please share more details. Which parts of that snippet provide randomness?

Saud Khan · Accepted Answer · 2015-12-26 01:10:04Z

3

You can try this:

 function KeyGenerator($uid) {
    $tmp = '';
    for($z=0;$z<5;$z++) {
      $tmp .= chr(rand(97,122)) . rand(0,100);
    }
    $tmp .= $uid;
    return $tmp;
  }

answered Dec 26, 2015 at 1:10

Saud Khan

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RobAtStackOverflow · Accepted Answer · 2013-09-26 01:14:16Z

2

I have generated this code for you. Simple, short and (resonably) elegant.

This uses the base64 as you mentioned, if length is not important to you - However it removes the "==" using str_replace.

<?php
        echo  str_ireplace("==", "", base64_encode(time()));
?>

answered Sep 26, 2013 at 1:14

RobAtStackOverflow

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4 Comments

RobAtStackOverflow Over a year ago

Meh, use rtrim() instead!

user1592648 Over a year ago

I agree use rtrim(), also the last I checked == did not have uppercase and lowercase versions. So why use case-insensitive replacement?

I never knew about rtrim() - I will take this into account for the future, thanks! As for case insensitive, thats habit.

Please share more details. Which parts of that snippet provide randomness?

Emilio Gort · Accepted Answer · 2013-09-26 01:55:29Z

2

I use this function

usage:

 echo randomString(20, TRUE, TRUE, FALSE);

  /**
   * Generate Random String
   * @param Int Length of string(50)
   * @param Bool Upper Case(True,False)
   * @param Bool Numbers(True,False)
   * @param Bool Special Chars(True,False)
   * @return String  Random String
   */
  function randomString($length, $uc, $n, $sc) {
      $rstr='';
      $source = 'abcdefghijklmnopqrstuvwxyz';
      if ($uc)
          $source .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
      if ($n)
          $source .= '1234567890';
      if ($sc)
          $source .= '|@#~$%()=^*+[]{}-_';
      if ($length > 0) {
          $rstr = "";
          $length1= $length-1;
          $input=array('a','b','c','d','e','f','g','h','i','j,''k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z')  
          $rand = array_rand($input, 1)
          $source = str_split($source, 1);
          for ($i = 1; $i <= $length1; $i++) {
              $num = mt_rand(1, count($source));
              $rstr1 .= $source[$num - 1];
              $rstr = "{$rand}{$rstr1}";
          }
      }
      return $rstr;
  }

edited Sep 26, 2013 at 1:55

answered Sep 26, 2013 at 1:14

Emilio Gort

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23 Comments

$uc == 1, $n == 1 :-S

Emilio Gort Over a year ago

@zerkms 1 is true, 0 is false

echo improve(constant(Alix),True); --- it throws a MayBeAnotherDay exception :-(

@JoseDavidGarciaLlanos: OP = Original Poster = YOU. =)

@EmilioGort: I never said it needed to be. You can just drop it.

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Charles · Accepted Answer · 2014-11-28 15:35:45Z

1

I'm using this one to generate dozens of unique strings in a single go, without repeating them, based on other good examples above:

$string = chr(mt_rand(97, 122))
          . substr(md5(str_shuffle(time() . rand(0, 999999))), 1);

This way, I was able to generate 1.000.000 unique strings in ~5 seconds. It's not THAT fast, I know, but as I just need a handful of them, I'm ok with it. By the way, generating 10 strings took less than 0.0001 ms.

answered Nov 28, 2014 at 15:35

Charles

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Comments

Vipin Kumar R. Jaiswar · Accepted Answer · 2014-12-24 06:34:14Z

JavaScript Solution:

function randomString(pIntLenght) {  
  var strChars = “0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz”;
  var strRandomstring = ”;

  for (var intCounterForLoop=0; intCounterForLoop < pIntLenght; intCounterForLoop++) {
      var rnum = Math.floor(Math.random() * strChars.length);
      strRandomstring += strChars.substring(rnum,rnum+1);
  }
   return strRandomstring;
}

alert(randomString(20));

Reference URL : Generate random string using JavaScript

PHP Solution:

function getRandomString($pIntLength = 30) {
      $strAlphaNumericString     = ’0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ’;

      $strReturnString         = ”;

      for ($intCounter = 0; $intCounter < $pIntLength; $intCounter++) {
           $strReturnString .= $strAlphaNumericString[rand(0, strlen($strAlphaNumericString) - 1)];
      }
      return $strReturnString;
}

echo getRandomString(20);

Reference URL : Generate random String using PHP

PavelŠ · Accepted Answer · 2015-08-18 05:28:39Z

1

This function returns random lowercase string:

function randomstring($len=10){
 $randstr='';
 for($iii=1; $iii<=$len; $iii++){$randstr.=chr(rand(97,122));};
 return($randstr);
};

answered Aug 18, 2015 at 5:28

PavelŠ

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Comments

Bex · Accepted Answer · 2015-12-29 10:30:36Z

1

I find that base64 encoding is useful for creating random strings, and use this line:

base64_encode(openssl_random_pseudo_bytes(9));

It gives me a random string of 12 positions, with the additional benefit that the randomness is "cryptographically strong".

answered Dec 29, 2015 at 10:30

Bex

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Comments

Salar · Accepted Answer · 2016-02-13 12:18:49Z

1

to generate strings consists of random characters, you can use this function

public function generate_random_name_for_file($length=50){
    $key = '';
    $keys = array_merge(range(0, 9), range('a', 'z'));
    for ($i = 0; $i < $length; $i++) {
        $key .= $keys[array_rand($keys)];
    }
    return $key;
}

answered Feb 13, 2016 at 12:18

Salar

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user985366 · Accepted Answer · 2017-11-29 11:17:29Z

1

It really depends on your requirements.

I needed strings to be unique between test runs, but not many other restrictions.

I also needed my string to start with a character, and this was good enough for my purpose.

$mystring = "/a" . microtime(true);

Example output:

a1511953584.0997

answered Nov 29, 2017 at 11:17

user985366

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4 Comments

microtime does not use any random parts, and starting with a fixed letter doesn't provide any more randomness

user985366 Over a year ago

@NicoHaase I didn't claim either of those two things, so not sure why you comment on this (and downvote?)