counting files

I have a web page that displays an image. I would like to randomize which image it displays when the page loads. Every possible image will be the same dimensions and file format. Each image will be named a consecutive number begining with 1. The code I am using is: $number = rand(1, 10); $file = $number . "." . "gif"; echo"<img src = 'random_images/$file'>"; I'm wondering if there is a way to count how many files are in the random_images directory, so I can dynamically set the range of my rand(). This way I can add images to the random_images directory without having to increase the range in the php code. Thanks! Nick