PHP generates n non-repeating random number instances detailed _php tutorial

I used to give you a talk about generating multiple random numbers, let me introduce an example of PHP generation n non-repeating random numbers, if you are interested, we can refer to.

This is not a difficult task to implement, but I have learned a lot.

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/** * Generate a certain number of distinct random numbers * @param int $min, $max Specify the range of random numbers * @param int $max * @param int $num Specify the number of builds * @return Array */ Fun Ction Unique_rand ($min, $max, $num) { $count = 0; $return = array (); while ($count < $num) { $return [] = Mt_rand ($min, $max); $return = Array_flip (Array_flip ($return)); $count = count ($return); } Shuffle ($return); Return $return; }

The Mt_rand () function is used when generating random numbers. The average speed of this function generates random numbers four times times faster than Rand ().
Removing duplicate values in the array uses the "rollover" method, which uses Array_flip () to swap the array's key and value two times. This approach is much faster than using Array_unique ().
Before returning an array, use Shuffle () to assign a new key name to the group, guaranteeing that the key name is 0-n consecutive digits. If you do not do this, you may cause the key name to be discontinuous when you delete duplicate values, causing the traversal to be cumbersome.

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