How to create a random string using PHP?

Question

I know that the rand function in PHP generates random integers, but what is the best way to generate a random string such as:

Original string, 9 chars

$string = 'abcdefghi'; 

Example random string limiting to 6 chars

$string = 'ibfeca'; 

UPDATE: I have found tons of these types of functions, basically I'm trying to understand the logic behind each step.

UPDATE: The function should generate any amount of chars as required.

Please comment the parts if you reply.

Answer 1

If you want to allow repetitive occurences of characters, you can use this function:

function randString($length, $charset='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789') {     $str = '';     $count = strlen($charset);     while ($length--) {         $str .= $charset[mt_rand(0, $count-1)];     }     return $str; } 

The basic algorithm is to generate <length> times a random number between 0 and <number of characters> − 1 we use as index to pick a character from our set and concatenate those characters. The 0 and <number of characters> − 1 bounds represent the bounds of the $charset string as the first character is addressed with $charset[0] and the last with $charset[count($charset) - 1].