PHP generates random strings (3 methods)_php tips

If a user registers to generate a random password, the user also needs to generate a random password to reset the password. A random password is a string of fixed length. The article summarizes several methods of generating random strings.
Method 1

1. Generate a random integer between 33 – 126, such as 35.

2. Convert 35 into the corresponding ASCII code character, such as 35 corresponding to #.

3. Repeat the above steps 1 and 2 n times to connect into an n-digit password.

This algorithm mainly uses two functions. The mt_rand (int $min, int $max) function is used to generate random integers, where $min – $max is the range of ASCII codes. Here it is 33-126, which can be used as needed. Adjustment range, for example, 97 – 122 bits in the ASCII code table correspond to the English letters a – z. For details, please refer to the ASCII code table; chr (int $ascii) function is used to convert the corresponding integer $ascii into the corresponding character.

function create_password($pw_length =  
{ 
$randpwd = ”; 
for ($i = 0; $i < $pw_length; $i++) 
{ 
$randpwd .= chr(mt_rand(33, 126)); 
} 
return $randpwd; 
} 
// 调用该函数，传递长度参数$pw_length = 6 
echo create_password(6); 

Method 2

1. Preset a string $chars, including a – z, A – Z, 0 – 9, and some special characters.

2. Randomly pick a character from the $chars string.

3. Repeat the second step n times to get a password of length n.

function generate_password( $length = 8 ) { 
// 密码字符集，可任意添加你需要的字符 
$chars = ‘abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/&#63;|'; 
$password = ”; 
for ( $i = 0; $i < $length; $i++ ) 
{ 
// 这里提供两种字符获取方式 
// 第一种是使用 substr 截取$chars中的任意一位字符； 
// 第二种是取字符数组 $chars 的任意元素 
// $password .= substr($chars, mt_rand(0, strlen($chars) – 1), 1); 
$password .= $chars[ mt_rand(0, strlen($chars) - 1) ]; 
} 
return $password; 
} 

Method 3

1. Preset a character array $chars, including a – z, A – Z, 0 – 9, and some special characters.

2. Randomly select $length elements from the array $chars through array_rand().

3. According to the obtained key name array $keys, take out the characters from the array $chars and concatenate the string. The disadvantage of this method is that the same characters will not be retrieved repeatedly.

function make_password( $length = 8 ) 
{ 
 
// 密码字符集，可任意添加你需要的字符 
$chars = array(‘a', ‘b', ‘c', ‘d', ‘e', ‘f', ‘g', ‘h', 
‘i', ‘j', ‘k', ‘l','m', ‘n', ‘o', ‘p', ‘q', ‘r', 's', 
‘t', ‘u', ‘v', ‘w', ‘x', ‘y','z', ‘A', ‘B', ‘C', ‘D', 
‘E', ‘F', ‘G', ‘H', ‘I', ‘J', ‘K', ‘L','M', ‘N', ‘O', 
‘P', ‘Q', ‘R', ‘S', ‘T', ‘U', ‘V', ‘W', ‘X', ‘Y','Z', 
‘0′, ‘1′, ‘2′, ‘3′, ‘4′, ‘5′, ‘6′, ‘7′, ‘8′, ‘9′, ‘!', 
‘@','#', ‘$', ‘%', ‘^', ‘&', ‘*', ‘(‘, ‘)', ‘-', ‘_', 
‘[', ']‘, ‘{‘, ‘}', ‘<', ‘>', ‘~', ‘`', ‘+', ‘=', ‘,', 
‘.', ‘;', ‘:', ‘/', ‘&#63;', ‘|'); 
 
// 在 $chars 中随机取 $length 个数组元素键名 
$keys = ($chars, $length); 
$password = ”; 
for($i = 0; $i < $length; $i++) 
{ 
// 将 $length 个数组元素连接成字符串 
$password .= $chars[$keys[$i]]; 
} 
return $password; 
} 

Time efficiency comparison

We use the following PHP code to calculate the running time of the above three random password generation functions to generate a 6-digit password, and then conduct a simple comparison of their time efficiency. The final result is:

Method 1: 9.8943710327148E-5 seconds
Method 2: 9.6797943115234E-5 seconds
Method three: 0.00017499923706055 seconds
It can be seen that the execution time of method one and method two are similar, while the running time of method three is slightly longer.
By comparing the implementation process of the three methods and comparing the time efficiency, I learned three methods of generating random strings in PHP. I hope it will be helpful to everyone in the future.