Explain how to use the Array_rand function in PHP _php tips

Objective

The Array_rand () function randomly selects one or more elements from an array and returns. From an array of random out of n values, with Array_rand () can be easily implemented, when facing a large array, we will worry about his efficiency, performance problems.

I tested that when 20 values were randomly taken out of an array of size 10,000, array_rand($arr, 20) The program took only about 0.005s and was highly efficient. Usually do not encounter such a large array bar, so we do not have to worry about array_rand efficiency problems.

At the same time, I used a different method of random numbers.

$arr = Array (1,2,3,4,5...9999); 
For ($i =0 $i <20; $i + +) 
{ 
 $rands = Mt_rand (0,9999); 
 $AA [] = $arr [$rands]; 
}

It only takes about 0.005s to run the program.

instances, random arrays

function Make_password ($length = 8) 
{ 
 //password character set, you can add any character you need 
 $chars = Array (' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' G '), ' H ', 
 ' I ', ' j ', ' K ', ' l ', ' m ', ' n ', ' o ', ' P ', ' Q ', ' R ', ' s ', 
 ' t ', ' u ', ' V ', ' w ', ' x ', ' y ', ' z ', ' A ', ' B ', ' C ', ' D ', c6/> ' E ', ' F ', ' G ', ' H ', ' I ', ' J ', ' K ', ' L ', ' M ', ' N ', ' O ', ' 
 P ', ' Q ', ' R ', ' S ', ' T ', ' U ', ' V ', ' W ', ' X ', ' Y ', ' Z ', ' 
 0 ', ' 1 ', ' 2 ', ' 3 ', ' 4 ', ' 5 ', ' 6 ', ' 7 ', ' 8 ', ' 9 ', '! ', 
 ' @ ', ' # ', ' $ ', '% ', ' ^ ', ' & ', ' * ', ' (', ') ', '-', ' _ ', 
 ' [ ', '] ', ' {', '} ', ' < ', ' > ', ' ~ ', ' ', ' + ', ' = ', ', ', ', ', ', ', ', ', ', ' 
 ., ' | '); 
 $length array element key 
 $keys = Array_rand ($chars, $length) are randomly taken in the $chars; 
 $password = '; 
 for ($i = 0; $i < $length; $i + +) 
 {//phpfensi.com 
  //Connect $length array elements to string 
  $password. = $chars [$keys [$i]] ; 
 } 
 return $password; 
}

I suspect that the Array_rand algorithm might be the way it was done. So take the random value in the array, rest assured bold use Array_rand bar.

Summarize

The above is the entire content of this article, I hope that the study or work to bring certain help.