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
Could someone show me how this is done?
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), $digits, '0', STR_PAD_LEFT);
I usually just use RAND() http://php.net/manual/en/function.rand.php
e.g.
rand ( 10000 , 99999 );
for your 5 digit random number
You can use rand($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);
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 $x = 11
FgHmqpTR3Ox
O9BsNgcPJDb
1v8Aw5b6H7f
haH40dmAxZf
0EpvHL5lTKr
Treat your number as a list of digits and just append a random digit each time:
function n_digit_random($digits) {
$temp = "";
for ($i = 0; $i < $digits; $i++) {
$temp .= rand(0, 9);
}
return (int)$temp;
}
Or a purely numerical solution:
function n_digit_random($digits)
return rand(pow(10, $digits - 1) - 1, pow(10, $digits) - 1);
}
function random_numbers($digits) {
$min = pow(10, $digits - 1);
$max = pow(10, $digits) - 1;
return mt_rand($min, $max);
}
Tested here.
the simplest way i can think of is using rand function with str_pad
<?php
echo str_pad(rand(0,999), 5, "0", STR_PAD_LEFT);
?>
In above example , it will generate random number in range 0 to 999.
And having 5 digits.
rand(1000, 9999); works more faster than x4 times rand(0,9);
benchmark:
rand(1000, 9999) : 0.147 sec.
rand(0,9)x4 times : 0.547 sec.
both functions was running in 100000 iterations to make results more explicit
do it with a loop:
function randomWithLength($length){
$number = '';
for ($i = 0; $i < $length; $i++){
$number .= rand(0,9);
}
return (int)$number;
}
rand or mt_rand will do...
usage:
rand(min, max);
mt_rand(min, max);
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;
}
Well you can use as simple php function mt_rand(2000,9000) which can generate a 4 digit random number
mt_rand(2000,9000)
this simple script will do
$x = 4;//want number of digits for the random number
$sum = 0;
for($i=0;$i<$x;$i++)
{
$sum = $sum + rand(0,9)*pow(10,$i);
}
echo $sum;
This is another simple solution to generate random number of N digits:
$number_of_digits = 10;
echo substr(number_format(time() * mt_rand(),0,'',''),0,$number_of_digits);
Check it here: http://codepad.org/pyVvNiof
function rand_number_available($already_mem_array,$boundary_min,$boundary_max,$digits_num)
{
$already_mem_array_dim = count($already_mem_array); // dimension of array, that contain occupied elements
// --- creating Boundaries and possible Errors
if( empty($digits_num) ){
$boundary_dim = $boundary_max - $boundary_min;
if($boundary_dim <= 0){
$error = -1; // Error that might happen. Difference between $boundary_max and $boundary_min must be positive
}else{
$error = -2; // Error that might happen. All numbers between, $boundary_min and $boundary_max , are occupied, by $already_mem_array
}
}else{
if($digits_num < 0){ // Error. If exist, $digits_num must be, 1,2,3 or higher
$error = -3;
}elseif($digits_num == 1){ // if 'one-figure' number
$error = -4; // Error that might happen. All 'one-figure' numbers are occupied, by $already_mem_array
$boundary_min = 0;
$boundary_max = 9;
$boundary_dim = $boundary_max-$boundary_min;
}elseif($digits_num == 2){ // if 'two-figure' number
$error = -5; // Error that might happen. All 'two-figure' numbers are occupied, by $already_mem_array
$boundary_min = 10;
$boundary_max = 99;
$boundary_dim = $boundary_max-$boundary_min;
}elseif($digits_num>2){ // if 'X-figure' number. X>2
$error = -6; // Error that might happen. All 'X-figure' numbers are occupied, by $already_mem_array. Unlikely to happen
$boundary_min = pow(10, $digits_num-1); // stepenovanje - graduation
$boundary_max = pow(10, $digits_num)-1;
$boundary_dim = $boundary_max-$boundary_min;
}
}
// -------------------------------------------------------------------
// --- creating response ---------------------------------------------
if( ($already_mem_array_dim <= $boundary_dim) && $boundary_dim>0 ){ // go here only if, there are AVAILABLE numbers to extract, and [difference] $boundary_dim , is positive
do{
$num = rand($boundary_min,$boundary_max);
}while( in_array($num, $already_mem_array) );
$result = $num;
}else{
$result = $error; // Limit that happened
}
return $result;
// -------------------------------------------------------------------
}
This function works perfectly with no repeats and desired number of digits.
$digits = '';
function randomDigits($length){
$numbers = range(0,9);
shuffle($numbers);
for($i = 0; $i < $length; $i++){
global $digits;
$digits .= $numbers[$i];
}
return $digits;
}
You can call the function and pass the number of digits for example:
randomDigits(4);
sample results:
4957 8710 6730 6082 2987 2041 6721
Original script got from this gist
Please not that rand() does not generate a cryptographically secure value according to the docs:
http://php.net/manual/en/function.rand.php
This function does not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a cryptographically secure value, consider using random_int(), random_bytes(), or openssl_random_pseudo_bytes() instead.
Instead it is better to use random_int(), available on PHP 7 (See: http://php.net/manual/en/function.random-int.php).
So to extend @Marcus's answer, you should use:
function generateSecureRandomNumber($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.
you people really likes to complicate things :)
the real problem is that the OP wants to, probably, add that to the end of some really big number. if not, there is no need I can think of for that to be required. as left zeros in any number is just, well, left zeroes.
so, just append the larger portion of that number as a math sum, not string.
e.g.
$x = "102384129" . complex_3_digit_random_string();
simply becomes
$x = 102384129000 + rand(0, 999);
done.
来源：https://stackoverflow.com/questions/8215979/php-random-x-digit-number