C# get MD5 of all files in a directory.

 public string getMD5(string filename) // File name.
        {
            using (var md5 = MD5.Create())
            {
                using (var stream = File.OpenRead(filename)) // Supports files > 2 GB unlike reading all lines.
                {
                    return BitConverter.ToString(md5.ComputeHash(stream)).Replace("-", "").ToLower();
                    //Creates a "normal" MD5 string.
                }
            }
        }

string[] files = Directory.GetFiles(/* Directory goes here*/); // Gets all files in a folder and puts it into an array.

foreach (string file in files) // loop over each file making file = "C:\Wallpaper\image.png" etc
{
        string MD5 = getMD5(file); // See the function definition above.
        // more code here to compare it to a history etc
}
/*

There's probably waaaay more efficient ways to do this

*/