Possible Duplicate:
PHP: How to generate a random, unique, alphanumeric string?
I'm creating the image hosting website. I need to create a unique and five letters string (case sensitive) for an image, like an example -> imgur.com/srM0U
I have seen many examples, but they are not unique or not case sensitive. Generated string I will use for an image filename, I think imgur uses a unique strings.
Please help with a piece of code