PHP mt_rand() Function

The 'mt' prefix in function's name stands for Mersenne Twister. The mt_rand() function returns a random integer using the Mersenne Twister Random Number Generator algorithm. This function is a drop−in replacement for PHP's rand() function and is four times faster. The default range is between 0 and the platform−specific mt_getrandmax() value (2147483647 on 64−bit systems).

Syntax

mt_rand() : int
mt_rand(int $min, int $max) : int

Parameters

Return Value

Returns a random integer between min and max (inclusive) using the Mersenne Twister algorithm. This function is not suitable for cryptographic purposes.

Example 1: Basic Usage

Generate random numbers with and without specified range ?

<?php
    echo "mt_rand() = " . mt_rand() . "<br>";
    echo "mt_rand(1, 10) = " . mt_rand(1, 10) . "<br>";
    echo "mt_rand(100, 999) = " . mt_rand(100, 999) . "<br>";
?>

mt_rand() = 1804289383
mt_rand(1, 10) = 7
mt_rand(100, 999) = 542

Example 2: Float Parameters

When float values are passed, they are automatically converted to integers ?

<?php
    echo "mt_rand(10.5, 50.95) = " . mt_rand(10.5, 50.95) . "<br>";
    echo "mt_rand(2.8, 8.9) = " . mt_rand(2.8, 8.9) . "<br>";
?>

mt_rand(10.5, 50.95) = 31
mt_rand(2.8, 8.9) = 5

Example 3: Getting Maximum Value

Check the maximum possible random value on your system ?

<?php
    echo "Maximum mt_rand value: " . mt_getrandmax() . "<br>";
    echo "Random between 0 and max: " . mt_rand(0, mt_getrandmax()) . "<br>";
?>

Maximum mt_rand value: 2147483647
Random between 0 and max: 1598374920

Conclusion

The mt_rand() function provides fast, high−quality random number generation using the Mersenne Twister algorithm. Use it for general purposes but avoid it for cryptographic applications where random_int() is preferred.