字符串中的唯一编号 - php

Question

I have some strings containing alpha numeric values, say

asdf1234,

qwerty//2345

etc..

I want to generate a specific constant number related with the string. The number should not match any number generated corresponding with other string..

Answer 1

Does it have to be a number?

You could simply hash the string, which would give you a unique value.

echo md5('any string in here');

Note: This is a one-way hash, it cannot be converted from the hash back to the string.

This is how passwords are typically stored (using this or another hash function, typically with a 'salt' method added.) Checking a password is then done by hashing the input and comparing to the stored hash.

edit: md5 hashes are 32 characters in length.

Take a look at other hash functions:
http://us3.php.net/manual/en/function.crc32.php (returns a number, possibly negative)
http://us3.php.net/manual/en/function.sha1.php (40 characters)