Three ways to generate random strings in PHP

This article mainly introduces three methods of generating random strings in PHP. Interested friends can refer to it. I hope it will be helpful to everyone.

Method 1

1. Generate a random integer between 33 and 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 to 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, The range can be adjusted as needed. 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; the 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 
$chars = ‘abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/?|&#39;; 
$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. Use array_rand() to randomly select $length elements from the array $chars.

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 
$chars = array(‘a', ‘b', ‘c', ‘d', ‘e', ‘f', ‘g', ‘h', 
‘i', ‘j', ‘k', ‘l','m', ‘n', ‘o', ‘p', ‘q', ‘r', 's', 
‘t', ‘u', ‘v', ‘w', ‘x', ‘y','z', ‘A', ‘B', ‘C', ‘D', 
‘E', ‘F', ‘G', ‘H', ‘I', ‘J', ‘K', ‘L','M', ‘N', ‘O', 
‘P', ‘Q', ‘R', ‘S', ‘T', ‘U', ‘V', ‘W', ‘X', ‘Y','Z', 
‘0′, ‘1′, ‘2′, ‘3′, ‘4′, ‘5′, ‘6′, ‘7′, ‘8′, ‘9′, ‘!', 
‘@','#', ‘$', ‘%', ‘^', ‘&', ‘*', ‘(‘, ‘)', ‘-', ‘_', 
‘[&#39;, &#39;]‘, ‘{‘, ‘}&#39;, ‘<&#39;, ‘>&#39;, ‘~&#39;, ‘`&#39;, ‘+&#39;, ‘=&#39;, ‘,&#39;, 
‘.&#39;, ‘;&#39;, ‘:&#39;, ‘/&#39;, ‘?&#39;, ‘|&#39;); 
 
// 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 3 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 one: 9.8943710327148E-5 seconds
Method two: 9.6797943115234E-5 seconds
Method three: 0.00017499923706055 seconds You can see the method The execution time of Method 1 and Method 2 are similar, while the running time of Method 3 is slightly longer.

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