generating a random code in php? - php

Question

i know this might seem silly, but i want to generate a random code of 8 characetrs, only numbers or letters using php. i needs this to generate a password for each user that signs up, thanks

Answer 1

I would rather use md5 to generate passwords
But you can use something like this if you want a custom:
function createRandomPassword() {
$chars = "abcdefghijkmnopqrstuvwxyz023456789";
srand((double)microtime()*1000000);
$i = 0;
$pass = '' ;
while ($i <= 7) {
$num = rand() % 33;
$tmp = substr($chars, $num, 1);
$pass = $pass . $tmp;
$i++;
}
return $pass;
}

Answer 2

What about something like this, for ease:
$pass = substr(md5(uniqid(mt_rand(), true)) , 0, 8);

Answer 3

A good or efficient method for doing this is:
public function generateRandomString($length = 8) {
$characters = '0123456789abcdefghijklmnopqrs092u3tuvwxyzaskdhfhf9882323ABCDEFGHIJKLMNksadf9044OPQRSTUVWXYZ';
$charactersLength = strlen($characters);
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[rand(0, $charactersLength - 1)];
}
return $randomString;
}
By changing $length variable you can generate alphanumeric code according to your need.

Answer 4

<?php
$uniqid = uniqid();
$rand_start = rand(1,5);
$rand_8_char = substr($uniqid,$rand_start,8);
?>

Answer 5

This work like charm and you can choose the type of characters that will be generated like:
"upper_case", "lower_case", "number", "special_character"
function create_random_code($length = 8, $in_params = [])
{
$in_params['upper_case'] = isset($in_params['upper_case']) ? $in_params['upper_case'] : true;
$in_params['lower_case'] = isset($in_params['lower_case']) ? $in_params['lower_case'] : true;
$in_params['number'] = isset($in_params['number']) ? $in_params['number'] : true;
$in_params['special_character'] = isset($in_params['special_character']) ? $in_params['special_character'] : false;
$chars = '';
if ($in_params['lower_case']) {
$chars .= "abcdefghijklmnopqrstuvwxyz";
}
if ($in_params['upper_case']) {
$chars .= "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
}
if ($in_params['number']) {
$chars .= "0123456789";
}
if ($in_params['special_character']) {
$chars .= "!##$%^&*()_-=+;:,.";
}
return substr(str_shuffle($chars), 0, $length);
}
To use it:
echo create_random_code(
6,
[
'upper_case' => true,
'lower_case' => true,
'number' => true,
'special_character' => false
]
);

Answer 6

Use base64_encode(), feed it some rand() numbers, and cut off the first 8 characters, which are definitely letters or numbers. That's not a totally random combination due to the input being just integers. But it's good enough for default user-passwords. (Else use rand() via chr() before encoding.)

Answer 7

PHP has a rand function (and also a mt_rand function that the docs claim is faster.)
So do something like this:
$i = 0;
$pwd = "";
while ( $i < 10) {
if (mt_rand() % 2 == 0) {
$pwd .= rand();
} else {
$pwd .= char(rand());
// http://php.net/manual/en/function.chr.php
}
$i += 1;
}

Answer 8

For your purposes, you can use the following to generate random codes:
bin2hex(random_bytes(10))
Note that here we use random_bytes, which was introduced in PHP 7 and uses a cryptographic random generator, something that is important if you want random codes to be hard to guess. random_int was also introduced in PHP 7 and likewise uses a cryptographic random generator.
Many other solutions for random value generation, including those involving time(), microtime(), uniqid(), rand(), mt_rand(), str_shuffle(), array_rand(), and shuffle(), are much more predictable and are unsuitable if the random string will serve as a password, a bearer credential, a nonce, a session identifier, a "verification code" or "confirmation code", or another secret value.
The code above generates a string of 20 hexadecimal characters (0 to 9, or A to F). If you want to use a bigger character set (such as all upper-case letters, all lower-case letters, and the 10 digits), this is a more involved process, but you have to use random_int rather than rand(), mt_rand(), str_shuffle(), etc., if the string will serve as a password, a "confirmation code", or another secret value. See an answer to a related question.
I also list other things to keep in mind when generating unique identifiers, especially random ones.