How can I generate a random string using php and only once per day?

Question

I have code that generates random strings, but I want to generate random strings only once per day.

This is the code generating a random string by every page load. How can I achieve this?

function random_string($length) {
$key = '';
$keys = array_merge(range(0, 9), range('a', 'z'));

for ($i = 0; $i < $length; $i++) {
$key .= $keys[array_rand($keys)];
}

return $key;
}
$sehiradi = "diyarbakir";
$subdomainadi = "$sehiradi."."".random_string(5);

You need to find some type of storage system (File/Database) to persist this data between page loads. — Blue, Oct 11 '18 at 20:56
Store the random string generated on a day in database. On every session load, check if a string already exists in the database for current date. If yes, return that; else generate a new one and store in the DB — Madhur Bhaiya, Oct 11 '18 at 20:56
you could also echo the results from an included file and run a crontab — Funk Forty Niner, Oct 11 '18 at 20:57
@MadhurBhaiya im not registering the code & subdomain in database i only need create random string once per day — Şahin Coşkun, Oct 11 '18 at 21:00
@FunkFortyNiner im creating crontab for deleting cache but every another pages creating another random string im only want one random string by per day — Şahin Coşkun, Oct 11 '18 at 21:01
Ok, so check if it's today's date and run the file and exit. I've done that before. — Funk Forty Niner, Oct 11 '18 at 21:02
How random it needs to be? A hash function like `sha1('someString'.date('Ymd').'someString');` solves for you? — Felippe Duarte, Oct 11 '18 at 21:03
@FelippeDuarte If you're using `sha1()` probably no need to even include a suffix. A long enough prefix should be enough to avoid people guessing. — Blue, Oct 11 '18 at 21:06
@FelippeDuarte The OP already has a random function. They want to run it once per day. Or maybe they didn't explain themselves correctly. But seeing their *"This code generating random string by every loading page how can i do this?"* suggests it. — Funk Forty Niner, Oct 11 '18 at 21:07
So, why not `$sehiradi.substring(sha1('someString'.date('Ymd')),0,5)`? — Felippe Duarte, Oct 11 '18 at 21:10
@FunkFortyNiner you are right i have a function for random string generate. Im only want run it once per day and show all of my guests same string — Şahin Coşkun, Oct 11 '18 at 21:11
So do/try what I suggested earlier about checking if it's today's day/date. As I said, I've done that before with success. — Funk Forty Niner, Oct 11 '18 at 21:13
@FunkFortyNiner you have source code for check if its todays date? — Şahin Coşkun, Oct 11 '18 at 21:16
@ŞahinCoşkun read the comment thread, its been posted already twice — , Oct 11 '18 at 21:19
Sashin, see @FelippeDuarte 's answer. I had a different one-liner but it's not in this PC that I'm on. But that looks good to me. — Funk Forty Niner, Oct 11 '18 at 21:24

score 2 · Accepted Answer · edited Oct 11 '18 at 21:40

2

You can achieve the same result using a hash function with the current date.

$sehiradi.substr(sha1('someString'.date('Ymd')),0,5);

This will work for you, as the hash will always bring the same result with the same input. Everyday, the function will use a different input value, as the day changes.

EDIT: Using your values you can have:

$sehiradi = "diyarbakir";
$subdomainadi = $sehiradi.substr(sha1('someString'.date('Ymd')),0,5);

Please replace 'someString' with some key that you have in mind. The point is to make it hard for someone to know the source of your "random" string.

edited Oct 11 '18 at 21:40

Funk Forty Niner

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answered Oct 11 '18 at 21:19

Felippe Duarte

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I'd upvote but I'm out of them right now. Pretty fancy ;-) I'd say that *"that's the ticket".* – Funk Forty Niner Oct 11 '18 at 21:22
Thank you for source. I tried like this $sehiradi = "diyarbakir"; $subdomainadi = $sehiradi(sha1('someString'.date('Ymd')),0,5); but it goes Call to undefined function diyarbakir() in .. – Şahin Coşkun Oct 11 '18 at 21:27
Edited with example of use. – Felippe Duarte Oct 11 '18 at 21:31
Thank you for the edit. Not my first language. Trying my best here :). – Felippe Duarte Oct 11 '18 at 21:42

score 0 · Answer 2 · answered Oct 11 '18 at 21:04

0

Have you tried looking into php cookies and storing it into a cookie file which has a ttl for 1 day? I only say this cause you mentioned you didn't want to store it in the database

answered Oct 11 '18 at 21:04

Moe

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cookies are user unique, what if he wants the same string for all users? – Oct 11 '18 at 21:07
Yes I want same string for all users but only one day another day another string for all users – Şahin Coşkun Oct 11 '18 at 21:08
then I would suggest storing it to a txt file with the date generated. @FrankerZ is right he needs a storage system. – Moe Oct 11 '18 at 21:08

score 0 · Answer 3 · answered Oct 11 '18 at 21:11

0

Since you don't want to store this information in a database and might not want to use cookies as they are user specific, here is a different approach:

Use the current Date (only day, month and year) as the seed for your random number generator. This will make it so it changes each day and is the same for all users without saving a single bit of data.

answered Oct 11 '18 at 21:11

Ciciboy1

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this is more of a comment to which in so many words, I've said already and a few times. – Funk Forty Niner Oct 11 '18 at 21:14
How can i add current date function to my code ? Any idea? – Şahin Coşkun Oct 11 '18 at 21:17
@FunkFortyNiner well... Not really... Your approch would be to check if today is still a specific day, which means you need to keep the time when you generated the last string. – Ciciboy1 Oct 11 '18 at 21:26
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@Ciciboy1 No, that isn't it. I'd of placed an answer of my own but couldn't since a one-liner I wrote a few years ago, is on a different PC that I'm on now and can't remember how I did it and it was weirdly slick *lol!*. – Funk Forty Niner Oct 11 '18 at 21:27
@FunkFortyNiner now im really interested in how you did that without saving anything anywhere, please tag me when you find your solution – Ciciboy1 Oct 11 '18 at 21:30
@Ciciboy1 Heh! Yeah... I like to fool around with code and some crazy thoughts sometimes. I wrote a "quasi table/column" bind for an sql prepared statement once using contants (tables/columns cannot be binded in a prepared statement) *theoretically*. I've got that too on that other PC. Well, if I think of it and I find it anytime soon, sure I'll share it in the answers area and you could get it off there :-) – Funk Forty Niner Oct 11 '18 at 21:32

How can I generate a random string using php and only once per day?

3 Answers3