php random x digit number

Question

I need to create a random number with x amount of digits.

So lets say x is 5, I need a number to be eg. 35562 If x is 3, then it would throw back something like; 463

Answer 1

Following is simple method to generate specific length verification code. Length can be specified, by default, it generates 4 digit code.

function get_sms_token($length = 4) {

    return rand(
        ((int) str_pad(1, $length, 0, STR_PAD_RIGHT)),
        ((int) str_pad(9, $length, 9, STR_PAD_RIGHT))
    );
}

echo get_sms_token(6);

Answer 2

Here is a simple solution without any loops or any hassle which will allow you to create random string with characters, numbers or even with special symbols.

$randomNum = substr(str_shuffle("0123456789"), 0, $x);

where $x can be number of digits

Eg. substr(str_shuffle("0123456789"), 0, 5);

Results after a couple of executions

98450
79324
23017
04317
26479

You can use the same code to generate random string also, like this

$randomNum=substr(str_shuffle("0123456789abcdefghijklmnopqrstvwxyzABCDEFGHIJKLMNOPQRSTVWXYZ"), 0, $x);

Results with $x = 11

FgHmqpTR3Ox
O9BsNgcPJDb
1v8Aw5b6H7f
haH40dmAxZf
0EpvHL5lTKr

Answer 3

Please not that rand() does not generate a cryptographically secure value according to the docs:

http://php.net/manual/en/function.rand.php

This function does not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a cryptographically secure value, consider using random_int(), random_bytes(), or openssl_random_pseudo_bytes() instead.

Instead it is better to use random_int(), available on PHP 7 (See: http://php.net/manual/en/function.random-int.php).

So to extend @Marcus's answer, you should use:

function generateSecureRandomNumber($digits): int {
   return random_int(pow(10, $digits - 1), pow(10, $digits) - 1);
}

function generateSecureRandomNumberWithPadding($digits): string {
   $randomNumber = random_int(0, pow(10, $digits) - 1);
   return str_pad($randomNumber, $digits, '0', STR_PAD_LEFT);
}

Note that using rand() is fine if you don't need a secure random number.

Answer 4

You can use rand($min, $max) for that exact purpose.

In order to limit the values to values with x digits you can use the following:

$x = 3; // Amount of digits
$min = pow(10,$x);
$max = pow(10,$x+1)-1);
$value = rand($min, $max);

Answer 5

You can use rand() together with pow() to make this happen:

$digits = 3;
echo rand(pow(10, $digits-1), pow(10, $digits)-1);

This will output a number between 100 and 999. This because 10^2 = 100 and 10^3 = 1000 and then you need to subtract it with one to get it in the desired range.

If 005 also is a valid example you'd use the following code to pad it with leading zeros:

$digits = 3;
echo str_pad(rand(0, pow(10, $digits)-1), $digits, '0', STR_PAD_LEFT);

Answer 6

function random_number($size = 5)
{
    $random_number='';
    $count=0;
    while ($count < $size ) 
        {
            $random_digit = mt_rand(0, 9);
            $random_number .= $random_digit;
            $count++;
        }
    return $random_number;  
}