How to get non-repeating random numbers in php

php method to obtain non-repeating random numbers: first randomly obtain a value within the interval through the "mt_random($min,$max)" method; then achieve non-repeating through two "key-value" exchanges Just a random number.

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Method of producing non-repeating random numbers in PHP

PHP built-in function does not repeat random numbers

Requirement: To generate an array, there are 10 elements in this array, all are integers, and they are 1- A non-repeating random number between 60.

Code:

Code example:

<?php   
function get_randoms($min,$max,$num){  
       $count = 0;  
       $res = array();  
       while($count<$num){  
    $res[] = mt_random($min,$max);  
    $res = array_flip(array_flip($res));   
    $count = count($res);  
        }  
        return $res;  
 }  
    
$result = get_randoms(1,60,10);  
?>

Here he uses $count to get the number of arrays. In the while loop, the number of result arrays is smaller than the target number. Through this, we get $count which is an array of target number.

During each cycle, through mt_random($min,$max), a value within the range is randomly obtained and stored in the array $res, and then through two key-value exchanges, that is, through The uniqueness of the array key ensures no duplication.

After I read the code of this logic, I couldn't help but fall into deep thought. What would you do if you didn't know the array_filp function?

To put it bluntly, it uses the uniqueness of the key so that there will be no duplication of random numbers. So can we simplify this problem?

Code example:

<?php   
function get_randoms($min,$max,$num){  
   $count = 0;  
   $res = array();  
   while($count<$num){  
   $key = mt_random($min,$max);  
   $res[$key] = $key;  
   $count = count($res);  
       }  
       return $res;  
}  
$result = get_randoms(1,60,10);  
?>

This solves this problem completely through the uniqueness of the array key. array_flip will not be used at all.

Summary:

1, because PHP provides a large number of built-in functions, their execution efficiency is very high. When you encounter a problem, try to use it to solve the problem as much as possible. This is convenient and fast.

2, PHP provides a large number of built-in functions, and the execution efficiency is also very high. However, although the efficiency is high, it still takes time to execute.

When you encounter a problem, don't do it blindly. You can first see the essence of the solution so that you can implement it skillfully.

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