PHP : Random string with numbers and letters

Mon, Oct 1, 2007

I thought that some of you might find it useful to learn how to generate a string with random numbers and letters. I wrote a quick function for generating a string like this. See it below :

function genRandomString() {
$length = 10;
$characters = ‘0123456789abcdefghijklmnopqrstuvwxyz’;
$string = ”;

for ($p = 0; $p < $length; $p++) {
$string .= $characters[mt_rand(0, strlen($characters))];
}

return $string;
}

letters, numbers, php, random, random string, string

This post was written by:

Antonie Potgieter - who has written 46 posts on Lost-In-Code.

I (Antonie Potgieter) am a software engineer/web developer located in South Africa. My full-time work is the management of Tribulant Software and the development of its software packages.

Contact the author

7 Comments For This Post

Jake Holman Says:
August 3rd, 2008 at 1:39 pm

Nice, came across this with a quick google search.

You have some syntax incorrect though. As it is now it will return something like 1f’q4w’432″2 - You don’t want those odd characters in there right?

Remove $string = “; it will get defined anyway. Also replace the ‘ around the $characters declaration and replace it with ” - it should look like this:

$characters = “0123456789abcdefghijklmnopqrstuvwxyz”;

That will mean the return will only have letters and numbers

lost-in-code Says:
August 3rd, 2008 at 1:54 pm

Hi Jake,

Thank you for the comment.

It is the encoding of Wordpress which causes those entities.
In reality, you have to replace them with proper html characters when you use the code. Here is a sample :

http://lost-in-code.com/wp-content/_randomstring.php

It works well.

All the best,
Antonie

Jake Holman Says:
August 7th, 2008 at 5:07 pm

Oh then I do apolosgize! Didn’t consider WP might be screwing things up.

But thank you for the snippet there. I used it in http://www.jakeisonline.com/s/ - something I was working on for work.

Thanks!