• 2
Votes
name

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Severity: Notice

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Backtrace:

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Line: 190
Function: _error_handler

File: /var/www/stackquestions.com/public_html/application/controllers/Questions.php
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Function: view

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Function: require_once

name Punditsdkoslkdosdkoskdo

How to generate random strings in PHP

Can somebody tell me how can I generate random strings in PHP

A class with some of the functions from the discussions above.

$options['numeric'] = true;
$options['uppercase'] = true;
$options['lowercase'] = true;
$new = new RandomString($options);

class RandomString
{
    /**
     * @var array
     */
    private $default = ['numeric' => true, 'uppercase' => true, 'lowercase' => true];

    /**
     * @var array
     */
    private $options;

    /**
     * array
     */
    private $whitelist = ['numeric', 'uppercase', 'lowercase'];

    /**
     * RandomString constructor.
     *
     * @param array $options
     */
    public function __construct(array $options = [])
    {
        $this->options = $this->default;
        if(!empty($options))
        {
            $options = array_intersect_key($options, array_flip($this->whitelist));
            if(empty($options))
            {
                $this->options = $this->default;
            }else
            {
                $this->options = $options;
            }
        }
    }

    /**
     * @return string
     */
    private function returnCharacters(){

        $options = $this->options;

        $numbers = '0123456789';
        $uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $lowercase = "abcdefghijklmnopqrstuvwxyz";

        $characters = '';
        if(isset($options['numeric']) && $options['numeric'] === true){
            $characters .= $numbers;
        }

        if(isset($options['uppercase']) && $options['uppercase'] === true){
            $characters .= $uppercase;
        }

        if(isset($options['lowercase']) && $options['lowercase'] === true){
            $characters .= $lowercase;
        }
        return $characters;
    }

    /**
     * @param $length
     * @param $quantity
     * @return string
     */
    public function randomString($length, $quantity) {

        $string = '';
        $characters = $this->returnCharacters();

        for ($j = 0; $j < $quantity; $j++) {
            for($i = 0; $i < $length; $i++){
                $string .= $characters[mt_rand(0, strlen($characters) - 1)];
            }
            $string .= "
";
        }
        return $string;
    }

    /**
     * @return array
     */
    public function getOptions()
    {
        return $this->options;
    }

    /**
     * @return mixed
     */
    public function getWhitelist()
    {
        return $this->whitelist;
    }
  • 1
Reply Report

There are better alternatives to this. Many was already posted so I give you only your stuff back with fixes:

<?php
    function RandomString()
    {
        global $randstring ;
        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $randstring = '';
        for ($i = 0; $i < 10 xss=removed>

Also you may be interested in:

<?php
    function RandomString()
    {
        global $randstring;
        $characters = str_split('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');
           array_filter ($characters,function($var)use($characters,&$randstring){
                $randstring .= $characters[rand(0, count($characters)-1)];
        });
        return $randstring;
    }

    RandomString();
    echo $randstring.'

'; //.. OR .. $randstring = ''; echo(RandomString()); ?>

Or another one:

<?php
    function s($length){
      for($i=0;
          ($i<$length) and
          (
              ($what=rand(1,3))

              and

              (
                  (
                      ($what==1) and
                      ($t=rand(48, 57)
                  )
                  ) or

                  (
                      ($what==2) and
                      ($t=rand(65, 90))
                  ) or

                  (
                      ($what==3) and
                      ($t=rand(97, 122)
                  )
                  )
              ) and
              (print chr($t))
          );

          $i++)

              ;
    }
    s(10);
?>
  • 1
Reply Report

In this method, you can choose the character length while creating.

<?php
    $random_string = "";
    $character_count = 12;
    for($i=1; $i <= $character_count; $i++)
    {
        $random_string .= chr(rand(97, 122));
    }
    echo $random_string;
?>
  • 2
Reply Report

To answer this question specifically, two problems:

  1. $randstring is not in scope when you echo it.
  2. The characters are not getting concatenated together in the loop.

Here's a code snippet with the corrections:

function generateRandomString($length = 10) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

Output the random string with the call below:

// Echo the random string.
// Optionally, you can give it a desired string length.
echo generateRandomString();
  • 1
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