Compare binary files in C#

Question

I want to compare two binary files. One of them is already stored on the server with a pre-calculated CRC32 in the database from when I stored it originally.

I know that if the CRC is different, then the files are definitely different. However, if the CRC is the same, I don't know that the files are. So, I'm looking for a nice efficient way of comparing the two streams: one from the posted file and one from the file system.

I'm not an expert on streams, but I'm well aware that I could easily shoot myself in the foot here as far as memory usage is concerned.

Answer 1

static bool FileEquals(string fileName1, string fileName2)
{
    // Check the file size and CRC equality here.. if they are equal...    
    using (var file1 = new FileStream(fileName1, FileMode.Open))
        using (var file2 = new FileStream(fileName2, FileMode.Open))
            return FileStreamEquals(file1, file2);
}

static bool FileStreamEquals(Stream stream1, Stream stream2)
{
    const int bufferSize = 2048;
    byte[] buffer1 = new byte[bufferSize]; //buffer size
    byte[] buffer2 = new byte[bufferSize];
    while (true) {
        int count1 = stream1.Read(buffer1, 0, bufferSize);
        int count2 = stream2.Read(buffer2, 0, bufferSize);

        if (count1 != count2)
            return false;

        if (count1 == 0)
            return true;

        // You might replace the following with an efficient "memcmp"
        if (!buffer1.Take(count1).SequenceEqual(buffer2.Take(count2)))
            return false;
    }
}