PHP Development Application: A method for generating random strings

The use of PHP to develop applications, especially web programs, often need to generate random passwords , such as user registration to generate random passwords, user reset password also need to generate a random password. Random password is a string of fixed length, here I collected several methods to generate random strings, for your reference.

Method One :

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

2, convert 35 to the corresponding ASCII code characters, such as 35 corresponding #

3, repeat the above 1, 2 steps n times, connected to the N-bit password

The algorithm mainly uses two functions, the Mt_rand (int $min, int $max) function is used to generate random integers, where $min – $max for the range of ASCII code, which takes 33-126, can adjust the range according to the need, such as the ASCII code table 97– 122-bit corresponding a–z letter, the specific reference to the ASCII table; the Chr (int $ascii) 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 the function, passing the length parameter $pw_length = 6 Echo Create_password (6);

Method Two :

1, preset a string $chars, including A–z,a–z,0–9, as well as some special characters

2. Randomly take a character in a $chars string

3, repeat the second step n times, can get a length of n password

function Generate_password ($length = 8) { Password character set, you can add any character you need $chars = ' abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&* ()-_ []{}<>~ ' +=,.;:/?] $password = '; for ($i = 0; $i < $length; $i + +) { Here are two ways to get a character The first is to use SUBSTR to intercept any one character in the $chars; The second is to take any element $chars the character array $password. = substr ($chars, Mt_rand (0, strlen ($chars)-1), 1); $password. = $chars [Mt_rand (0, strlen ($chars)-1)]; } return $password; }

function Generate_password ($length = 8) {
Password character set, you can add any character you need
$chars = ' abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&* ()-_ []{}<>~ ' +=,.;:/?]

$password = ';
for ($i = 0; $i < $length; $i + +)
{
Here are two ways to get a character
The first is to use SUBSTR to intercept any one character in the $chars;
The second is to take any element $chars the character array
$password. = substr ($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 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 ', ' 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 ', '! ', ' @ ', ' # ', ' $ ', '% ', ' ^ ', ' & ', ' * ', ' (', ') ', '-', ' _ ', ' [', '] ', ' {', '} ', ' < ', ' > ', ' ~ ', ' ', ' + ', ' = ', ', ', ', ', ', ', ' '.', ';', ':', '/', '?', ''); Randomly taking $length array element key name in a $chars $keys = ($chars, $length); $password = '; for ($i = 0; $i < $length; $i + +) { To 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 3 random password generation functions above to generate 6-bit passwords, and then make a simple comparison of their time efficiency.

<?php function Getmicrotime () { List ($usec, $sec) = Explode ("", Microtime ()); Return ((float) $usec + (float) $sec); } Record start time $time _start = Getmicrotime (); Here are the PHP code to execute, such as: Echo Create_password (6); Record End time $time _end = Getmicrotime (); $time = $time _end-$time _start; Total output Run time echo "Execution time $time seconds"; ?>

The final result is :

Method One: 9.8943710327148E-5 seconds

Method Two: 9.6797943115234E-5 seconds

Method Three: 0.00017499923706055 seconds

You can see that method one and method two have the same execution time, and method three runs a little longer.

Original: http://www.ludou.org/how-to-create-a-password-generator-using-php.html