Several methods for generating random passwords in php

The mt_rand (int $ min, int $ max) function is used to generate random integers. $ min & amp; ndash; $ max indicates the ascii code range. here, 33-126 is used, you can adjust the range as needed, as shown in figure

The mt_rand (int $ min, int $ max) function is used to generate a random integer. $ min-$ max indicates the ascii code range. here, 33-126 is used. you can adjust the range as needed, for example, The-characters in the ascii code table correspond to letters a-z. for details, refer to the ascii code table. The chr (int $ ascii) function is used to convert the corresponding integer $ ascii to the corresponding characters, the code is as follows:

1. Function create_password ($ pw_length = 8)
2. {
3. $ Randpwd = '';
4. For ($ I = 0; $ I <$ pw_length; $ I ++)
5. {
6. $ Randpwd. = chr (mt_rand (33,126 ));
7. }
8. Return $ randpwd;
9. }
10. // Call this function to pass the length parameter $ pw_length = 6
11. Echo create_password (6 );

Method 2:

1. preset a string $ chars, including a-z, a-z, 0-9, and some special characters;

2. a random character in the $ chars string;

3. Repeat step 2 n times to obtain a password with a length of n. the code is as follows:

1. Function generate_password ($ length = 8 ){
2. // Password character set, which can be any character you need
3. $ Chars = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789! @ # $ % ^ & * ()-_ [] {}<> ~ '+ = ,.;:/? | ';
4. $ Password = '';
5. For ($ I = 0; $ I <$ length; $ I ++)
6. {
7. // Two character acquisition methods are provided here
8. // Use substr to intercept any character in $ chars;
9. // The second method is to take any element of the character array $ chars.
10. // $ Password. = substr ($ chars, mt_rand (0, strlen ($ chars)-1), 1 );
11. $ Password. = $ chars [mt_rand (0, strlen ($ chars)-1)];
12. }
13. Return $ password;
14. }

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. extract the string from the array $ chars based on the obtained key name array $ keys.

The disadvantage of this method is that the same characters are not repeated and the code is as follows:

1. Function make_password ($ length = 8)
2. {
3. // Password character set, which can be any character you need
4. $ Chars = array ('A', 'B', 'C', 'D', 'e', 'F', 'G', 'H ',
5. 'I', 'J', 'K', 'L', 'M', 'n', 'O', 'P', 'Q', 'R ','s ',
6. 'T', 'u', 'V', 'W', 'X', 'y', 'z', 'A', 'B', 'C ', 'D ',
7. 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'n ', 'o ',
8. 'P', 'Q', 'R','s ', 'T', 'u', 'V', 'W', 'X', 'y ', 'Z ',
9. '0', '1', '2', '3', '4', '5', '6', '7', '8', '9 ', '! ',
10. '@', '#', '$', '%', '^ ','&','*','(',')','-', '_',
11. '[', ']', '{', '}', '<', '> ','~ ', ''',' + ',' = ',',',
12. '.',';',':','/','? ',' | ');
13. // Random $ length array element key names in $ chars
14. $ Keys = ($ chars, $ length );
15. $ Password = '';
16. For ($ I = 0; $ I <$ length; $ I ++)
17. {
18. // Concatenate $ length array elements into strings
19. $ Password. = $ chars [$ keys [$ I];
20. }
21. Return $ password;
22. }

Comparison of time efficiency: We use the following php code to calculate the running time of the above three random password generation functions to generate a six-digit password, and then make a simple comparison of their time efficiency, the code is as follows:

1. Function getmicrotime ()
2. {
3. List ($ usec, $ sec) = explode ("", microtime ());
4. Return (float) $ usec + (float) $ sec );
5. }
6. // Record start time
7. $ Time_start = getmicrotime ();
8. // Put the php code to be executed here, for example:
9. // Echo create_password (6 );
10. // Record end time
11. $ Time_end = getmicrotime ();
12. $ Time = $ time_end-$ time_start;
13. // Output the total running time
14. Echo "execution time $ time seconds ";