PHP - Convert characters to a number

Question

Let's say I have a string like this:

whateverthisis123 #_-

I want to convert this string into a number within a number interval forexample within 1-1000.

The above string could for example be converted into

This comes with a few rules:

The string could contain every character.
The number should feel random but cannot be. The same string should always return the same number.
Longer string should not make the number higher. Should feel random.
aaa should not give a number like 222. Should feel random.
It should accept the interval for example 1 up to 1000.
"thisstring" and "thisstring1" are alike. The numbers should still not be alike.

Is there a built in function for this in PHP? If not, any clever idea how to create something like this?

Maybe it's easier if first converting in to MD5? http://www.php.net/manual/en/function.md5.php

You can convert it to md5, take out the first 3 digit, and comvert them back to decimal*1000/4095 and you will get the number range max possible at 1000 — Poomrokc The 3years, Apr 04 '14 at 06:50
Thanks for vote me as the correct answer!! I got +25 reps , thanks haha — Poomrokc The 3years, Apr 04 '14 at 10:37

score 2 · Answer 1 · answered Apr 04 '14 at 06:41

2

You're essentially describing a hash function. MD5 looks like the way to go. If you need to convert it to a number you could intval() it. To keep it between 1-1000, use $number % 1000.

Note: If this has to do with security/passwords, it's a bad idea.

answered Apr 04 '14 at 06:41

Jeff

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@OP If you're using this as a method of security in any aspect, please consider using [bcrpyt](http://stackoverflow.com/questions/4795385/how-do-you-use-bcrypt-for-hashing-passwords-in-php) as opposed to MD5. MD5's lack of uniqueness makes it vulnerable to multiple attacks. – Ohgodwhy Apr 04 '14 at 06:42
No, I'm not going to use it for security. I might have a URL to a quote and on that URL I want a "random" avatar image. This function will create a link to for example 387.jpg for that URL. – Jens Törnell Apr 04 '14 at 07:37
1

Sounds like a perfect use case then. Just wanted to make sure! – Jeff Apr 04 '14 at 07:39
I tested it and almost always I get 0 in result. It seems like the intval returns 0 in many cases. – Jens Törnell Apr 04 '14 at 10:17

score 1 · Accepted Answer · edited Dec 20 '19 at 14:02

Extended from my comment, here is a full code example (more fun way than just hash..)

 <?php
  function numberout(string $input)
      {
         $hash=md5($input);
         $calculate=hexdec(substr($hash,0,3)); //take out 3 digits
         $maxhex=4095; //3 digit hex ,65535 for 4 digit hex and so on...
         $out = ($calculate*1000)/$maxhex;
         return round($out);
      }
 ?>

Sorry if this is programmartically wrong, I was used to c# and I haven't test this yet. So if there is any error I hope someone to edit it

PHP - Convert characters to a number

2 Answers2