Random number in range [min - max] using PHP

问题:

Is there a way to generate a random number based on a min and max?

For example, if min was 1 and max 20 it should generate any number between 1 and 20, including 1 and 20?

回答1:

<?php
  $min=1;
  $max=20;
  echo rand($min,$max);
?>

回答2:

In a new PHP7 there is a finally a support for a cryptographically secure pseudo-random integers.

int random_int ( int $min , int $max )

random_int — Generates cryptographically secure pseudo-random integers

which basically makes previous answers obsolete.

回答3:

A quicker faster version would use mt_rand:

$min=1;
$max=20;
echo mt_rand($min,$max);

Source: http://www.php.net/manual/en/function.mt-rand.php.

NOTE: Your server needs to have the Math PHP module enabled for this to work. If it doesn't, bug your host to enable it, or you have to use the normal (and slower) rand().

回答4:

(rand() % ($max-$min)) + $min

or

rand ( $min , $max )

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

回答5:

rand(1,20)

Docs for PHP's rand function are here:

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

Use the srand() function to set the random number generator's seed value.

回答6:

I have bundled the answers here and made it version independent;

function generateRandom($min = 1, $max = 20) {
    if (function_exists('random_int')):
        return random_int($min, $max); // more secure
    elseif (function_exists('mt_rand')):
        return mt_rand($min, $max); // faster
    endif;
    return rand($min, $max); // old
}

回答7:

Try This one. It will generate id according to your wish.

function id()
{
 // add limit
$id_length = 20;

// add any character / digit
$alfa = "abcdefghijklmnopqrstuvwxyz1234567890";
$token = "";
for($i = 1; $i < $id_length; $i ++) {

  // generate randomly within given character/digits
  @$token .= $alfa[rand(1, strlen($alfa))];

}    
return $token;
}