How to prevent repeated random numbers from being generated in PHP

The content of this article is to share with you how to prevent repeated random numbers in PHP. It has a certain reference value. Friends in need can refer to it

1. PHP built-in function implements non-repeating random numbers

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

<?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 $count represents the number of result arrays, which in the while loop makes the number of result arrays less 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.

2. Implement non-repeating random numbers without using functions

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, the uniqueness of the key is used to prevent 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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