How to generate non-repeating random numbers in PHP

This article mainly shares with you the method of producing non-repeating random numbers in PHP, hoping to help everyone.

1. PHP built-in function to implement non-repeating random numbers

Requirement: To generate an array, in this array There are 10 elements, all of which are integers and non-repeating random numbers between 1 and 60.
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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