hash - C# MD5 hasher example

Question

Edit: I've retitled this to an example as the code works as expected.

I am trying to copy a file, get a MD5 hash, then delete the copy. I am doing this to avoid process locks on the original file, which another app writes to. However, I am getting a lock on the file I've copied.

File.Copy(pathSrc, pathDest, true);

String md5Result;
StringBuilder sb = new StringBuilder();
MD5 md5Hasher = MD5.Create();

using (FileStream fs = File.OpenRead(pathDest))
{
    foreach(Byte b in md5Hasher.ComputeHash(fs))
        sb.Append(b.ToString("x2").ToLower());
}

md5Result = sb.ToString();

File.Delete(pathDest);

I am then getting a 'process cannot access the file' exception on File.Delete()'.

I would expect that with the using statement, the filestream would be closed nicely. I have also tried declaring the filestream separately, removing using, and putting fs.Close() and fs.Dispose() after the read.

After this, I commented out the actually md5 computation, and the code excutes, with the file being deleted, so it looks like it's something to do with ComputeHash(fs).

Answer 1

Import the name space

using System.Security.Cryptography;

Here is the function that returns you md5 hash code. You need to pass the string as parameter.

public static string GetMd5Hash(string input)
{
        MD5 md5Hash = MD5.Create();
        // Convert the input string to a byte array and compute the hash.
        byte[] data = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input));

        // Create a new Stringbuilder to collect the bytes
        // and create a string.
        StringBuilder sBuilder = new StringBuilder();

        // Loop through each byte of the hashed data 
        // and format each one as a hexadecimal string.
        for (int i = 0; i < data.Length; i++)
        {
            sBuilder.Append(data[i].ToString("x2"));
        }

        // Return the hexadecimal string.
        return sBuilder.ToString();
}