PHP generates random strings

During PHP development, especially for web programs, you often need to generate random passwords. for example, if you register a user to generate a random password, you also need to generate a random password to reset the password. A random password is a string with a fixed length. The following describes several methods for generating random strings.

During PHP development, especially for web programs, you often need to generate random passwords. for example, if you register a user to generate a random password, you also need to generate a random password to reset the password. A random password is a string with a fixed length. The following describes several methods to generate random strings for your reference:

Method 1:

1. Generate a random integer in 33-126, for example, 35,

2. convert 35 to corresponding ASCII characters, for example, 35 #

3. Repeat steps 1 and 2 n and connect them to a n-bit 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 ASCII code range, here, the range is 33-126. you can adjust the range as needed. for example, 97-122 characters in the ASCII code table correspond to English letters a-z. for details, refer to the ASCII code table. chr (int $ ascii) the function is used to convert the corresponding integer $ ascii to the corresponding character.

Function create_password ($ pw_length = 8) {$ randpwd = "; for ($ I = 0; $ I <$ pw_length; $ I ++) {$ randpwd. = chr (mt_rand (33,126);} return $ randpwd;} // call this function and pass the length parameter $ 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. random character in $ chars string

3. Repeat step 2 n times to obtain a password with a length of n.

Function generate_password ($ length = 8) {// you can add the character set $ chars = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 as needed! @ # $ % ^ & * ()-_ [] {}<> ~ '+ = ,.;:/? | '; $ Password = "; for ($ I = 0; $ I <$ length; $ I ++) {// Two character acquisition methods are provided here. // The first method is to use substr to intercept any character in $ chars; // The second type is to take any element of the character array $ chars // $ password. = substr ($ chars, mt_rand (0, strlen ($ chars)-1), 1); $ password. = $ chars [mt_rand (0, strlen ($ chars)-1)];} return $ password ;}

Function make_password ($ length = 8) {// password character set. you can add the required characters $ 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', '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 ′,'! ',' @ ',' # ',' $ ',' % ',' ^ ','&','*','(',')', '-', '_', '[', ']', '{', '}', '', '~ ', ''',' + ',' = ',',','.',';',':','/','? ',' | '); // Random $ length array element key name $ keys = array_rand ($ chars, $ length) in $ chars; $ password = "; for ($ I = 0; $ I <$ length; $ I ++) {// concatenate $ length array elements into strings $ 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 six passwords, and then compare their time efficiency.

The final result is:

Method 1: 9.8943710327148E-5 seconds

Method 2: 9.6797943115234E-5 seconds

Method 3: 0.00017499923706055 seconds

We can see that method 1 and method 2 have almost the same execution time, while Method 3 has a longer running time.

You can select a method that suits your needs.