PHP generates random passwords

PHP development applications, especially website programs, often need to generate random passwords, such as user registration to generate random passwords, the 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 in the 33–126, such as 35,
2, convert 35 to the corresponding ASCII character, such as 35 corresponding #
3, repeat the above 1, 2 steps n times, connected to n-bit password
The algorithm mainly uses two functions, Mt_rand (int $min, int $max) function is used to generate random integers, where $min – $max the range of ASCII code, here take 33-126, you can adjust the range as necessary, such as the ASCII code table 97– 122 digits corresponding to the a–z of the English alphabet, specific reference to the ASCII code 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 this function, pass length parameter $pw_length = 6
Echo Create_password (6);
Method Two:
1, preset string $chars, including a–z,a–z,0–9, and some special characters
2. Randomly take a character in a $chars string
3, repeat the second step n times, can get the length of the password of n

Function Generate_password ($length = 8) {
//password character set, you can add any character you want
$chars = ' [email protected]#$%^&* () -_ []{}<>~ ' +=,.;:/?| ';
$password = ';　　　　
for ($i = 0; $i < $length; $i + +)
{
//two ways to get a character here
//The first is to use SUBSTR to intercept any one character in $chars;
　　　　The second 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;
}
Method Three:
1, a preset character array $chars, including a–z,a–z,0–9, and some special characters
2, by Array_rand () from the array $chars randomly selected $length elements
3, according to the obtained key an array group $keys, remove the character stitching string from the array $chars. The disadvantage of the method is that the same characters are not repeated.

Function Make_password ($length = 8)
{
//password character set, you can add any character you want
$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 take $length number of element key names in the $chars
$keys =array_rand ($chars, $length);
$password = "; 　　
for ($i = 0; $i < $length; $i + +)
{
//concatenate $length array elements into a string
$password. = $chars [$keys [$i]];
}
return $password;
}
Time Efficiency comparison
We use the following PHP code to generate a 6-bit password run time for 3 random password generation functions, thus making a simple comparison of their time efficiency.

function Getmicrotime ()
{
List ($usec, $sec) = Explode ("", Microtime ());
return (float) $usec + (float) $sec);
}

Record start time
$time _start = Getmicrotime ();

This puts the PHP code to execute, such as:
Echo Create_password (6);

Record End time
$time _end = Getmicrotime ();
$time = $time _end-$time _start;
Total time of output run
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

It can be seen that the execution time of method one and method two is similar, and the running time of method Three is a little bit short.

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PHP generates random passwords