(PHP 5, PHP 7 >= 5.6.3)
gmp_random_bits — Random number
Generate a random number. The number will be between
0 and (2 ** bits) - 1.
bits must greater than 0, and the maximum value is restricted by available memory.
bitsThe number of bits.
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
A random GMP number.
Example #1 gmp_random_bits() example
<?php
$rand1 = gmp_random_bits(3); // random number from 0 to 7
$rand2 = gmp_random_bits(5); // random number from 0 to 31
echo gmp_strval($rand1) . "\n";
echo gmp_strval($rand2) . "\n";
?>
以上例程会输出：
3 15